Right now, I think we just need to keep up with everything happening in the world and all that the EU and governments come up with to seize people's assets for the state's benefit. USDT will probably be exchangeable far into the future.
However, I take note of what
@JackAlabama says, that USDT can be seized by the American authorities at any time as it stands. So, if the EU manages to implement the same, you definitely shouldn't have your USDT in an EU country. The question is whether they're safe in the UK and CH - I don't know, but it's a good question.