Thank you for your personal opinion on the matter. I am, of course, a tad more optimistic, although I mostly agree on 3); the servers required to run an instance with multiple multi-crew ships, must cost quite a lot of money to rent, I think that the bill to have all that processing power would be prohibitive.
I remember reading on the Valve development blog that Left 4 Dead had to use network trickery to allow syncing all zombies across all players. Now that was 10 years ago, 4 years ago I though that in 4 years there would be improvements in cost of this infrastructure, but if they are planning to sync every. Single. Item. in all ships, I think only an incredibly fast internet connection would do it.
In the end, I think they will have to severely limit the amount of players in each instance, but CIG knows best.