Not all will stick with it. I dont know any percentages, but in my experience its fairly low. Many will never see a pack.
Most boy scout troops do quite a lot of car camping, with scattered high-adventure activites mixed in. Scout campouts are for learning and demonstrating skills, and working on merit badge requirements. Not just for fun. Car camping with patrol boxes,and a big troop trailer keeps everything organized and available to camp frequently,every month. It allows for parents to drop kid off on friday evening, and come back and pick them up on Sunday afternoon. If it was harder, campout participation would be low, and rank progress would suffer.
When they start camping every month, rain or shine, most do buy a decent quality tent with taped seams that will keep them dry. (they learn fast, all it takes is getting soaked once) Kelty, Eureka, ALPS, and even Coleman. The number of true cheapies diminishes. The ALPS gear when purchased from Scoutdirect, is unbeatable for quality for the price. But it is not light. Most tents weigh 5-7 lbs. This can be split between 2 scouts for backpacking, but honestly, is still really heavy and bulky. (My own goal when backpacking is to carry shelter wt of 1-1.5 lb/person).
I know what you are saying about sleeping bags and temps. At a campout last winter temp was in low 30s, my sons tentmate asked him thru chattering teeth "Im freezing, are you cold?". My son answered " No, Im actually toasty!". He has a good sleeping bag, while MOST still have bags that cost under $40.
There is a learning curve. Usually they start with the same cheap gear they used in cubs,but by the time they are 13 and ready for high-adventure, they have accumulated a servicable (but heavy) tent, maybe a decent sleeping bag (but its not light or packs small). Then they may get a 5.5-6 lb Kelty pack for christmas before they go to philmont, etc. That is why their packs still weigh 40 lbs when they hit the trail at philmont.
Cooking in boy scouts is done by Patrol, in groups. Stoves are shared equipment. You will only need one stove for every 3-4 boys, or something like that. Maybe two per patrol for backpacking. In car camping, we use big, stable, indestructible two burner gas stoves and 5 gal propane cylinders. 10 yr old boys cannot cook on backpacking stoves! They can barely cook on the big stable ones.
If you really want to get 2person tents that will be used in the future, look for 2P double wall tents that have included poles, and weigh in the 3-3.5lb range. MSR, Big Agnes, etc. That is only 1.5 lb eachor so when backpacking. These will be fairly small for 2 for car camping though for a few yrs. Most heavy dads couldnt even fit in one by themself, much less with another person. These tents are more expensive and confining than other tents that would work better for car camping.
In the years that pass before these kids are capable of real backpacking, lighter more durable items will also come to market.
Truthfully, I know where you are coming from. I took the same approach for my son and I. When he reached boy scouts I bought higher quality, lighter weight, smaller tents that could be used for backpacking. But I can say that those tents never will, because they are still too heavy by my current standards.