A sequel to ED would likely happen after this games lifetime which isn't over yet, they'd also probably go with the shared BGS and modes again since the spaceship customer base is a fairly niche one. Moving away from it would reduce the potential customer base.
For me the open only situation is pure pebcak, which is the reason I've never once bothered posting in Hotel California. Its an argument not worth having as the issue simply isn't the game. Personally I like mode choice, its one of the things I checked we had prior to buying in (along with the block function). Without it I wouldn't have got the game.
FDEV do deal with cheats, hackers and griefers they are just far too nice to name and shame so you can miss it. The info's out there on it if you look.
I don't expect you to believe that I am one of 18 people who no longer play but FDev have the means to verify, that means just in my little sphere alone they will not get any more of our money in its current form.
Not out of protest, just because for those who want open only it is too frustrating to play and as you have rightly said if you are not enjoying it why play it?
The most frustrating thing is it is not even about being in open only, it is %100 about 5C.
FDev could fix most of it tomorrow by just preventing a player from doing anything in PP that negatively affects your chosen power, but they haven't and doubt they will.
5C is the same as griefing and cheating as far as most PP players are concerned, and FDev refuse to fix it, despite asking for feedback multiple times over the years.
You can choose not to care about me and my 17 friends and Kek knows how many others, but that is short sighted because FDev are a business and the more players ED has the better it will be.
These forums have died, reddit has died, I don't mean doom I mean anyone being honest can not say there is even %10 of the posts there used to be on either site, so something has changed, whether you would like to care or not.
The easiest thing would be just code the game so you can not negatively affect a power from within, or split us from the solo pg guys and just give us two different instances, or even keep open and create "open PP" that has its own instance and bgs so that they are only adding and not taking anything from anyone.
Anything would be better than nothing, and that is all they have done for a long time.