I'm of the opinion that Coaster and Zoo have developed in such different ways, with such different player bases, that comparing the two is a dangerous form of "old think", and carries the risk (consciously or unconsciously) of biasing or privileging those elements that happen to be the same, as opposed to all the ways that Zoo is different and special. So with that huge caveat, (a reminder to myself of the pitfalls and the trap I'm about to enter), here are my initial thoughts on what subscriptions might mean for PZ:
I think "cash grab" is just customer-speak for "wise business decision", so I have no problem there.
As a post-development strategy, long after the hard-core fans have already gotten to enjoy the game, I think it's fine. I presume that Frontier has the statistics to back up the choice for Coaster (or they wouldn't have done it), such as how many new players at this late date only try the base game (so that even a month with the dlc subscription is a bonus), or how many new players at this point only come in for a limited time before moving on to another game. I also assume they factored in the numerous sales they have throughout the year too (another place where new customers are paying less than the veterans, but one that we all accept as normal and pay anyway because we want the content now, not x months from now).
Obviously, my hope is that PZ continues adding new animals in paid dlc forever. Meaning the post-development subscription model wouldn't come to PZ until forever plus x years from now! The idea of a subscription model while development is still occurring (which, again, I hope continues for a long time in PZ), gets a lot more tricky. I think they should stick to buying outright during the many, MANY years that PZ is still going to remain in development.
A few other things to consider:
1. Is the renewal process automatic, or do you opt in every month? This makes a big difference in how much Frontier will actually make (from people who maybe forget they are subscribed), and would also make a difference in whether I'd try it (in another game, of course. I'm ride or die for PZ).
2. Are there ways that the subscription model might actually HELP long-term players who already own the game outright, at no additional cost? For example, could the subscriptions from newbies help defray the cost of keeping the franchise servers working even longer after development than they might have otherwise? (Since unlike the other modes, we are reliant on a digital infrastructure that's outside of our own personal machines). These types of considerations change the equation and calculations for me, since it might mean that existing players are seeing a benefit, even if not formally announced. (ie. the free update is that the franchise servers would continue to exist for all players, precisely because the new subscriptions are making that possible).
3. Might subscription players transform the player base and help renew different game modes later in the game's life? After all, it's not merely a new purchasing model, but potentially a new style of players, and a chance to do new styles of advertising for a different set of players. For example, does it mean more players who are spending a month or two working through the career modes and scenario modes, as opposed to players who spend six months (or longer!) working to perfect a single sandbox zoo? Does it rejuvenate the franchise market, since you'll have new players trying things out, instead of just the old pros who have a million credits built up? Will we learn new tips and tricks from players who are seeing the game mechanics from different perspectives, instead of predominantly through the lens of Planet Coaster or Zoo Tycoon? (And will these forums be as open and engaging to people who bring perspectives and comparisons from other games, with the same energy and with the same enthusiasm that we are all responding to PC news right now? LOL!)
4. Does the prospect of eventual subscriptions (even if way in the distant future after development ends), nevertheless change player (buyer) behavior even while the game is still in development? Not so much for hardcore fans like all of us, but for casual folks who think "maybe I'll try it someday", for whom someday might come earlier if it's always going to be a buy situation, but who might wait and have someday come much later if they know it will change to subscriptions?
5. Does the prospect of eventual subscriptions (even if way in the distant future after development ends), nevertheless change dev behavior even while the game is still in development? I doubt this would happen overtly, but I can see it being a subtle influencer in a corporate culture sort of way. Is someone more likely to renew their subscription for another month because they haven't yet tried "flexicolor beam 2", or because they haven't built for a new animal? Will we see a subtle shift towards pieces and mechanics which may be either more basic or stylized-but easily-placeable, but which get people to renew their subscription who have only played for 1, 2 or 3 months, as opposed to more advanced tools, that take us 1, 2, or 3 years just to build and learn! Does it make it more likely that certain things might get fixed or updated (pathing difficulties, climbing difficulties, ease of management) because the devs are subtly encouraged to think of the player base as rolling waves of people with 1, 2, or 3 months of experience, as opposed to being told that they'll get better if they'd only practice for a decade.
6. Will reviewers, forum members, and content creators need to begin taking the possibility of future subscription players into account when reviewing new announcements, updates, and dlc? So in the same way that some reviewers will say "this will be helpful for franchise players" even if they themselves don't play in franchise, will we start seeing reviews that say "this will be great for eventual subscription players" or "this will be great for getting eventual subscription players to renew for more months" even if they themselves are going to own the game outright?
7. Similarly, might we see even more content creators engaging with the career and timed scenarios, as new waves of viewers come through who aren't intending (at least initially) to become long-term master builders in sandbox, but are looking for tips and tricks to get through the various goals and challenges? Subscriptions could lead more people to smash the subscribe button for creators too, and reward the ones who cater to their unique subscription-based play styles!
8. And finally, does the Bundling of all the dlc together make us think of them differently than when we're judging them one at a time? Is it more likely that someone who tries them for a month or two and decides they like the game is more likely to end up buying not merely specific dlc, but ALL of the dlc, because they have come to think of them as a package? Does it decrease the impact of historical decisions about the timing or roll-out of various elements, if they start to be seen as a collection? In 25 years, when subscribers are getting birds and fish and llamas and polar bears and kangaroos and binturong all in the same "package", will they even recognize the debates that we've all been having?