the concern (for m) on this, is as internet security continues to develop, what will be available in the future for expats ?

If you mean, in terms of being able to do 2FA and access websites, I hope more institutions move to using TOTP authentication (security keys or authenticator apps). SMS-based 2FA is awful from a security standpoint - scarcely better than asking me for the last 4 digits of my SSN as so many banks do for "verification" on voice calls - yet still so prevalent. IME it's mostly the newer / smaller brokerages (TradeStation, Tastyworks, M1 for example) and banks that use TOTP. There's also email authentication which is not ideal either, but is probably insensitive to your location.

I am trying to strip things down so within a couple of months of departure, and before actually establishing residency, my only accounts not explicitly supporting expats are unimportant in balance terms but useful otherwise. For example, I'd like to keep certain credit cards open because they have decades of history, but that does not require more than spending something on them once/year.