the idea that some restrictions will be kept in place for years is delusional.
This is true. They're desperate to get rid of restrictions which damage the economy and society.
Worries.about.a.third wave in the UK for instance when over half the population have been vaccinated and the lockdown only partially lifted doesn't sound realistic
The issue however, as Boris 'Pennywise' Johnson said, is that if there's another wave (with consequent mutations due to more hosts) on the continent, it could spread to the UK (or as he said "alas, it could wash up on our shores, alas"). Cases are rocketing in Poland (and contrary to what someone said earlier, the number of cases matters a lot due to the likelihood of more mutations emerging). Nevertheless, travel restrictions are extreme. I've just had to arrange a test here in PL before travel, a Day 2 and Day 8 test from a specified provider (paid in advance, £200) there, get a control number for the test and include that control number in a Locator Form which is scannable at the border and before travel. If Poland (or the country I'm changing planes in) is added to the Red List before travel, that would mean 10 days in a government approved hotel, payable in advance. Even without that, they check that you're quarantining at a specificed address. The travel rules are annoying and strict, however cases are falling there. Any more tightening of the rules, and there'll be almost no travel at all.
Most of the most vulnerable are likely to be vaccinated well before the autumn and the warmer weather will bring cases down.
Also true. In the UK, the vulnerable are all vaccinated now, and my category, not old, not ill, have all received the NHS letter with a code to register. In Poland, they'd better get a move on.