Good points. I don't know the answer either but there are lots of clues.
As of early February, over 4,000 variants had been identified since the start of the pandemic but most are not of concern, so we only hear about the handful that gain some kind of strong advantage for survival, like being more contagious or avoiding the vaccine antibodies.
We all know that the more cases there are in the community, the more chance there is of the virus throwing up a nasty variant. Lockdown is bringing cases down rapidly and in another couple of months, case numbers should be very low and easily monitored, fingers crossed. If the vaccine take-up stays as incredibly high as it is now, there won't be enough active infections to give the virus a good chance to whip up a killer variation.
It's now easier to monitor border arrivals and to test, track and trace all cases to clamp down on any variants... will be even easier once case numbers are low.
We have some of the best genome sequencing labs and expertise in the world here (we do the sequencing for roughly 50% of the world!) so if something scary crops up, we'll know about it and the vaccine will be tweaked.
Bottom line is, I guess I've made up my mind, from what we know, to see the future as bright... the justified doom and gloom of the past year has been absolutely exhausting and damaging. I plan to make the most of my 'get out of jail' vaccine and not worry about catching Covid now that it's unlikely to kill me... until I'm told there's something new to worry about of course!