I expect castles to be the biggest issue after the merge.
Initially, there will be many more orders than castles, but most of them with too few members to conquer a good castle.
So there will have to be order mergers, which creates a number of new problems:
- Which order to keep and which to abandon (=losing everything in the order treasury),
- Players who had been active on a number of the old pre-merge servers being unable to bring all their nice, long-played accounts into the same order due to multi restrictions.
I know I'm a bit extreme in that regard, with successful accounts on all servers, but I'm by no means the only one playing on more than one server. I know for a fact that a number of long-time players are actively playing high-level accounts on three, four, five or more servers -- so I'm not whining about myself here, but mentioning an issue that will be a problem for several others as well.
Scrapping multi-restrictions is probably not a good solution, since it would invite other problems. So in the end, the dedicated players will have to decide which one of their nice accounts they wanna keep playing, putting all their other accounts into limbo. R.I.P.