You're totally right. They all go about it differently. Though I feel that FDevs tactic of advertising a year of updates for 60$ and we'll only be getting half of that is a poor one. Perhaps my joke hit a bit too close to home for some people.
There are 2 things here though.
1. The timeline of releases
2. The number of updates included in the Horizons Season
As far as the announcement only one of these things has changed.
The only thing we know for certain. 2.1 has been delayed by about 6 weeks.
The stated reason for this is that they wanted to make sure the quality was good enough to release 2.1, if they had stayed with the original timeline then this would not have been the case.
Things that we can speculate on, the delay of 2.1 will have a knock on effect on 2.2 / 2.3 / 2.4. This may or may not be the case, but I would say it's more likely than not.
The number of updates included on the Season. I see no reason to speculate that Horizons will not contain the same amount of content as originally planned. So your $60 will get you the same amount of content, it just might take a bit longer to get it.
The timeline for Season 3. Most peoples expectation was that Seasons would last a year, so 3.0 would drop mid December just like 1.0 and 2.0. We know that there is a team working on 3.0 (and 4.0) so there is a chance that 3.0 will release before 2.x concludes, although I think this is unlikely.
I would say that it's highly unlikely that the headline features of any of the 2.x releases will be pushed back to season 3. If they are, for technical reasons, I would expect them to be free for season 2 owners in just the same way that the missions update in 2.1 is also available to owners of 1.6. I would speculate that the worst case scenario would be that 2.4 releases along side 3.1 or that 3.0 comes early next year. This will all depend on how important FD think getting 3.0 out for the Christmas buying frenzy is.
Bottom line. The content you're getting for your $60 hasn't changed, just the delivery date. Your not getting 1/2 the content, it's just a small delay. This is unfortunate, but better they release something that works that rush the release out to hit an arbitrary deadline.