That is not a good figure to gauge how profitable CoH2 is. It doesn't say how many of them buy anything, nor how interested they are in new DLC/Expansions/CoH3. Since Relic isn't making new DLC/Expansions for Coh2, we can assume it isn't profitable/worthwhile to make them. CoH2 base game has been on deep sale/bundles/even free, the base game is peanuts as far as generating additional revenue is concerned. Did Sega even get the pre-order money from Coh2, because I cannot find whether they won the lawsuit?
If AoE4 is a windows store exclusive (looks like the case), Relic is in a big trouble. Windows Store is a joke for PC exclusives, it is going to sell worse than DoW3.
It is likely COH2 made money since it sold well.
Most developers don't just endlessly churn out DLC / expansions, They want to make new games.