There are honestly far too many variables, including the batshit President of Brazil that someone else mentioned, to be absolutely positive about predictions. But there has been a lot of work done by epidemiologists, and the consensus is that (a) some new strains do appear to be more transmissible but that there is little evidence that they are more lethal, and (b) the vaccine strains may be slightly less effective in reducing transmission, but they are still very effective, and more effective than, say, the flu vaccine!
What many people fail to appreciate is that viruses mutate all the time. Constantly. Like all living organisms, they exist to reproduce and that is the measure of their success - survival. Contrary to how it is often portrayed, a successful virus transmits a lot and kills very little - if a virus has wiped out many people then who does it transmit to? So a cold virus is really successful (widespread, easy to catch, only the very vulnerable are at risk); and Ebola (easy to catch but deadly, so doesn't transmit as widely, and therefore easier to contain and eradicate) is actually rubbish as a virus and "unsuccessful".
Scientifically, all bets would be on reduced mortality, even without a vaccine, because a virus tends to mutate towards that easy transmission without being overly lethal - and because populations quickly start to develop and build natural defences. So whilst it is important not to underestimate this virus, there is actually not a shred of evidence that the worst case scenarios will play out. Unless, of course, you are entirely stupid and the President of Brazil.
Be respectful of any virus. But that doesn't mean living in fear. I have actually, unlike many people, seen Ebola. That is a seriously nasty virus. But, as I said, human ingenuity means that we are very capable of managing it. Some of the science that we learned dealing with that has actually contributed to vaccines we are now using for Covid. We will beat this and get past it - and in much quicker a time because of our science than we would have in days gone by.
Remember that this is, in the end, just nature. If not this, something else. Nature just "is" - it requires no grand design or plan.