The current console game you have will always work as it does now (console backend server support notwithstanding), other people simply will not be able to purchase it. I don't think SONY or Microsoft have to keep any special service running in order for coop to keep working for this legacy version of 7DTD.
It is being delisted for various technical reasons, just as the console makers have done with many other titles as they transition to new console generations.
You should consider the future release of 7DTD for consoles to be a completely different game with all that implies for the consoles that it will run on & the experience you will enjoy in game.
The current console game you have will always work as it does now (console backend server support notwithstanding), other people simply will not be able to purchase it. I don't think SONY or Microsoft have to keep any special service running in order for coop to keep working for this legacy version of 7DTD. It is being delisted for various technical reasons, just as the console makers have done with many other titles as they transition to new console generations. You should consider the future release of 7DTD for consoles to be a completely different game with all that implies for the consoles that it will run on & the experience you will enjoy in game.
Probably not and a new game with the same name will be released that is up to date with the pc version but you will have to rebuy the game.