Is there a plan in the future to be able to play on any server no matter the region you created the account in? For example having a NA acc but playing on London servers while travelling to London.
No plans right now. Your use case makes sense, but providing that support will only impact a very small part of the player base (e.g. those currently traveling outside their shard, or players with friends across the world who want to play together and have terrible latency).