The Kadet Kits have always been big sellers for CZ. I would be shocked if they didn't manufacture them again in the future.
CZ-UB (and most other manufacturers) don't make every single model in every year. They don't have the production capacity, and constantly switching over to other models kills Q.C. Certain CZ products "dry up" from time to time. Considering how hard it is to find .22LR ammunition right now, this may not be a big deal anyway.
Personally, I really don't understand what dedicated .22 LR pistols are supposed to achieve, unless it is just the fun and lower expense of shooting them. (Not saying that isn't valid, I'm just saying that would seem to be their only function/purpose.) If you hold out for the Kadet Kit, at least you will have the training benefit that AZ_CZ mentioned.
The only .22 handgun I've ever owned (still do) is a Jana Bison SAA clone from W. Germany. It is one of many el-cheapo SAA clones with both a .22LR and .22 Magnum cylinder that have been made in Europe ever since WWII. My father bought it used over there in 1966 from another NCO for $5 cash, with a lot of ammo thrown in. It's just about the worst. It only groups with expensive .22LR, if at all, and it has never grouped with any .22 Magnums we have found. Factor in gate-loading and the difficulty in cleaning it, and you have a born loser. I mention it only because I suspect that it soured me on .22 handguns for life.