There are certainly at least a couple of things that will emerge from data and/or studies over the next few weeks that will indicate the course of the next phase - not just antigen escape of the new mutant(s), but also whether there's any statistical significance behind the anecdotal reports of either B117 (UK) or 501.v2 (SA) causing severe disease at higher rates in young people than wild type.
(Vaguely-informed) speculation on the former follows:
The 10 501.v2 mutations are all in the parts of the virus that the vaccines target, and largely the natural immume response too (as they are the functional and/or most exposed parts). This obviously could well cause decreased efficacy of the 'lock-and-key' mechanism the induced antibodies use to target the virus. One should remember though that the spike protein is the part of the virus that has to 'lock-and-key' to our cells as well, so it doesn't have the freedom to be totally labile - it has to keep enough of its own 'key' shape to be able to infect - hopefully that also retains enough of its 'lock' shape for at least some of the wild-type/vaccine induced antibodies to work - enough to keep the damn thing under control in an infection to a) prevent serious disease and b) give the body's immune system time to make some new keys to fit these new locks. Bascially the challenge faced by the virus is to change its shape enough so that the antibody proteins can't recognise it, but the cell proteins that give it entry still can. This is not an easy thing to do.
The production methods for the main vaccine types are very fast and flexible as well - adding in the code to make the new versions of the spike protein should be able to be done very quickly (even a matter of weeks) - certainly long before most people have any chance of getting near a vaccine. I haven't heard if they're working on the new sequences yet, but I'd be very surprised if they're not doing at least some of the preliminary work already.
Because of the 'lock-and-key' element above it's likely that there's a finite number of mutations the virus can add to its spike protein in an attempt to evade immunity before it breaks it - it may well be that we have a short arms race with the bastard over the next little while, while we learn (substantially) all of its forms (yes, even its final form), and make a cocktail vaccine to cover all of them. It is unlikely to be able to do the endless polymorphism that flu does for instance. In the meantime it's reasonable to hope that imperfectly fitting immunity will have some (enough) protective effect on those who receive the vaccine early.