I assume your accusations of fatuosity are directed at sean99, given that it was he to whom I was responding, you know, Britains position relative to the G7 etc..
Of course this small island will progressively diminish relative to the rapid rise of the so-called 'emerging economies', many of them far more populous than the UK. The British economy, in common with those of the EU's big beasts, is stagnating relative to those emerging economies, and I doubt there's anything that will stop that shift. We are mature economies saddled with ageing populations. Europe's position in terms of world GDP has been falling for years. It's probably quite remarkable that we've hung on as long as we have.
Brexit has 'buggered' some businesses, undoubtedly, but given that only a relatively small percentage of UK businesses exported to the EU, and that EU exports accounted for only about 14% of GDP prior to (actual) brexit, it won't have 'buggered' by any means all of them, whilst many will have undoubtedly benefited, and will benefit in the future, from import substitution, and opening new markets. And, of course, many businesses have adapted to the new export rules. Business is well known for being extraordinarily adaptable.
The question of the UK's apparently diminished (smaller) economy relative to 'prior to the pandemic' remains unaddressed.