It really depends. I'm not saying it's impossible, but it would be really hard for Valorant to overtake CS in Europe.
The real question that will determine whether valorant can overtake CS in pure viewership will be the rise of the Asian scene. CS is too strongly rooted in Europe, yet Asia looked towards other games primarily, and is the world's biggest gaming market.
If Asia gets big on the bandwagon, then I could see valorant surpassing CS. Timing is unclear. I suppose we'll be able to see it evolve and make a more educated guess when Reykjavik, Berlin and end of year major happen.