A universal coronaviruses vaccine: Possible? Feasible? Realistic?

Given that COVID-19 is just the latest coronavirus-based pandemic, or fear of pandemic, to hit the globe, can we go beyond the current COVID-19 vaccines to create a universal coronavirus jab? Wired explores the possibility. Even if they just, on average, offer 50 percent protection, that would make them somewhat like annual flu vaccines only on a much bigger scale. The question then would be, how much more, per year,  or every 2-3 years, would they have to be tweaked than the annual flu shot?

Also, once you're past pandemic fears, who's going to pay for this? By that, I'm not talking about paying for vaccine development. I'm talking about who's going to pay for annual distribution and administration of an annual COVID vaccine in non-pandemic times? A regular flu shot ain't free, at least not here in the non-national health care USofA, and a universal COVID vaccine would be orders of magnitude more pricey?

Next, back to the first paragraph. I said somewhat like annual flu vaccines. The flu jab, except in an especially off year, offers something like 70 percent protection, not 50 percent. Would a universal COVID vaccine at 50 percent protection be "worth it" on the issue of protection versus the costs of vaccine tweaking for virus evolution? Some virologists and vaccinologists need to weigh in.

Related?

Lawrence Wright has a long piece about COVID-19 variants and vaccine immunity. The whole thing is worth a read, but the shorter version? The UK variant appears to be no problem on the current vaccines, but the South African variant may indeed have more vaccine resistance. On the new Brazilian variant, it's too soon to say, but given anecdotes coming from that country, it's almost certainly more vaccine-resistant. And, it's not just the current Pfizer and Moderna vaccines. Any COVID vaccine that is mRNA based and targets a virus in the same way they do is vulnerable to having props knocked out from under it if the virus shows fairly rapid evolution.

My off the top of the head hunch is, no, it wouldn't be worth it for vaccinating the general population. Maybe the aged, infirm and other high risk, but not the general population.