So you would need a job offer, health insurance & min earnings that would cover your partner too, language skills.
OR you could buy your way in with a Golden Visa, which will cost around 500k euros (only applicable to a few EU countries)
What sort of jobs do you think EU countries might be looking for that they cannot fill within a bloc of 27 countries?
Do you think it might be people earning the average UK wage? or a specialist financier, international lawyer, scientist already employed by a European based company?
Perhaps impossible is too strong a word, very difficult might be better.
Then there is people who might wish to travel around europe for more than 3 months at a time, agree, you need to financially secure but i did it by working and travelling, not possible now or people, not the wealthy elite, who bought a small 2nd home or a canal boat, planning on retirement.. not possible to even live there for more than 90 out of a 180 days and that applies to the EU as a bloc.
Over 100k Brits used to work in the tourist sector pre Brexit in Europe, inc a friend of ours who was a cycling guide, he has residency for Spain (obtained it pre Brexit) BUT can only work in Spain, one of his main tours was the Pyrenees, can't venture into France.... no work visa and they like you to be under 50, he is 53 :(
Then there is the UK not in Horizon..... such a lose to UK science.
The world has moved on in the last 50 years since 1973, thinking that we can do what our parents did in 1965 is probably why we have Brexit.