I don't want to be pessimistic, but I'm just taking past French releases into account (especially the most recent ones for the last few years) to try to possibly keep some expectations in check, though hope is always welcome.
While we can be sure that we'll have all of the OG Dragon Ball available like this with this specific remastering process, it seems unlikely to me that it will be used for Dragon Ball Z too.
The reason is that - and you can correct me if I'm wrong and forgot something, of course - I think French DB releases usually use another master that's already done and ready to go, the latest one from the original country.
We've learned that they were ready to use existing masters for OG Dragon Ball, except I think no proper HD version justifying a Blu-ray release currently exists in Japan, am I right? So they planned on turning to another country and use the Selecta Vision that's ready for use, but ultimately couldn't bring themselves to feel it was good enough quality-wise and were "forced" to create their own remaster by the situation, as a last resort.
Now the thing is, I think I saw that there are Blu-rays of DBZ in Japan, I remember I saw news on the main Kanzenshuu website about the censorship of middle fingers, etc... If I'm not wrong and didn't make this up, and an acceptable remaster already exists, they'll likely go for it (and remasters like the DBZ movies are deemed acceptable, since as far as I know they were precisely used for the movies Blu-ray pack that was released here earlier this year, with the same censored middle fingers and all).
So while I think Dragon Ball Z may very well be coming after Dragon Ball for a French Blu-ray release (it would make sense and that could explain why our anime streaming service ADN is setting the DBZ episodes for "later in 2023" comared to all other DB shows coming in December and January), my bet is that they'll simply use the Japanese Blu-ray masters like they usually do.
Now, for a more hopeful side, we can hope that other countries will take notes on how this remaster was done and decide to apply a similar process, if not directly asking the French staff what they did, so that they can apply it to a new DBZ release themselves.
As for a GT release, there's some good and some bad to consider. The bad thing is that GT doesn't get a lot of releases around here, so who knows if they'll be willing to invest in a release if they think it won't be really popular.
The good thing is that I think it's similar to OG Dragon Ball in that there's currently no "acceptable" Blu-ray master as far as I know, meaning if they decide to release it, they'll probably do exactly what they're doing with OG Dragon Ball.
But I'm not saying that to bum you out, just what I think if I analyse the situation, but this set already proves that big surprises are possible when it comes to releases! Who knows, maybe after this set, they'll be like "actually, let's keep doing our own remasters exactly like this for Z too instead of using existing masters". I hope it happens if it can satisfy fans all around the world!