Yes we can see good moves in altcoin as btc dominance is going down but for old project this is the time to make new ATH so that they can go big in up coming year .
It's not all of the old project can go up in the upcoming year. Even in this year there are lots of old projects are getting abandoned.
The old projects have no power to compete with the new project and that means if old project will not be able moving to the new ATH as soon as possible.
I think that btc dominance is still remain stable but ethereum and some major coins were only eating really small percentage of bitcoin dominance.