A reluctance of one UK bank to open an account for an associated USC, currently, is not true for all UK banks, currently.
As far as can be ascertained, an account opened today by any bank carries no guarantee that the account can not be closed in 6 months time. (Good question for termed accounts.)
The discussions taking place to resolve the objections to FATCA include grandfathered accounts, accounts that are already in place and not new accounts, electronic searches of currently held information to establish a US tie verses deeper searches that may need to be done in the future for grandfathered accounts (and at what time in the future), the threshold value of the account that triggers searching, or reporting, etc.
The question is not "can I open a new UK bank account today as a US person" (Vadio excepted), but "will I be able to open a new bank account on 01 January 2013" or is it 01 January 2014?
If an agreement can be negotiated between the US and the 5 EU countries, it appears it will not be a problem. It's just too early to make definitive statements, one way or the other.
Could someone please give me the exact reference that says a UK bank is, by law, required to open a new account for any UKC residing in the UK?