I see a couple of problems if we stick with Race 07.
There is no doubt that the demand for race 07 leagues is decreasing, that means no matter how much advertising we do for the league it will always be hard to get only a couple of new drivers, that would be a lot easier if we switched to a newer platform and my personal favourite still is gsc.
The cars are great, there are a lot of F1 addon-circuits and the graphic is much improved compared to Race 07 without having very high system requirements. And of course the price is very affordable campared to rFactor 2.
And just as an example
here is the sign up thread of another RD GSC league.
One problem I see too is with things around the league like doing broadcasts and reviews.
Those are not primary issues but it is a big part of a racing league in my opinion.
The broadcasts we did this season where for sure a lot of fun for the drivers but everyone I tallked to including the commentators said that it wasnt much fun to watch, not due to driver abilities, due to the cars which didnt create much highlights.
Thats something which would change with a newer platform as well because they simply create more action.
Of course the decision about switching to a new platform shouldnt be made too quickly but games like GSC and rFactor 2 are as good as finished in terms of content and price so the choice for season 11 wont be much different.
So if we want to switch at all I'd recommend doing it for season 10 because in my opinion it would help the league a lot and there is a good chance to get as big as we used to be.