Yes, based on the top sellers list. We don't know any numbers, but this indicates that Ubisofts games are doing well on EGS, at least compared to other games. And we do know that certain other games like Satisfactory, WWZ and Snow Runner sold very well on EGS.
As I already said, this one is the worst indicator we have, it's manual and it's not regularly updated, they can pretty much use the positions as they want in order to show certain games they want to show (like C2077 that magically appeared out of nowhere when CDPR gave report)
Am I saying they aren't selling on EGS? no, just that you shouldn't trust that top seller list that much as it's not an automated system.
Another point is that Valhalla sold extremely well, more than any other Ubisoft game. Because lots of these sales were at full price, the revenue may be much higher than the revenue of Ubisofts older games on Steam.
This one is also funny because I remember discussing this by saying "wording is easy but they aren't sharing any figures" and IIRC Valhalla was the best AC release on PC in the first few days or something like that, which is a veeeery specific way of announcing it, is it a lie? no, don't think so, is it an indicator of them not coming back because their platform is exploding in popularity? don't think so either.
Keep in mind that most of the companies are shifting their strategies in order to get all the users, EA did it, MS did it, Sony is testing their waters too, and you will see others in the near future that are doing the same (and once something gets announced I will try to expand this in a dedicated post) so, is Ubisoft different? no, once they can, contractually speaking, come back, they will just to expand their own service, as
eonden said, the goal here is to get as many users as possible in your own services via accounts and subscriptions, so.... if EA was allowed to put their service on Steam, do you think Ubi won't consider this option too? it would be even a deeper conection between services than what they have on consoles, for example.
It's just a guess of course. Steam is the only one reporting concurrent users.
Yes and no, they report positions and size, however no specific numbers, which are tricky due to the highly dense areas of data, we can more or less see where's every game positioned at, but we won't know specifics, anyway, yeah, Valve sharing all the data they share makes it easier to track figures and games.