Some points to clear up:
- No one does surgical expansion of the mandible. Lots of people have tried it. No one likes to publish their failures. That's begging for a lawsuit. I'm sure it gets discussed quietly at conferences. On top of it, surgical expansion of both arches is technically challenging because the uncertainly is now doubled. Getting both to relapse the same, predictable amount is hard. If you want to expand the mandible, then there is only one decent option on the market right now and that's surgically facilitated orthodontics. There's maybe a dozen people on the planet with enough experience to do this right now, extra surgery, unpredictable relapse rates, and it's limited to about 5mm. DO to lengthen the mandible is also very rarely done, even in children. And it's the wrong movement, usually they need to be widened.
- You don't have to extract teeth but if you don't, there won't be enough room in the arches for them. So your orthodontist will expand the arches. And the teeth will sit near or even outside the margins of the bone. 60% of people have teeth like this but don't realize it and at all ages. When that happens, the teeth are unstable (likely to crowd again), roots get blunted, and gums tend to recede. It gets compounded by age, as the face shrinks and bones decalcify, esposing at risk teeth. These problems take decades to appear! I've already got recession on two teeth because they're tipped lingually. It's a s**tty choice to make but, objectively, removing 4 teeth to protect 24 other teeth down the line makes a lot of sense. Dr Posnick writes the same in his textbook.
- Airways get worse with age and most of us will get sleep apnea at some point. What differs largely is when we get it. Many won't get it until 80-90, some at 50, and some, like me, before the age of 5. Diagnosis rates are low because the symptoms are vague and come on gradually. The kinds of problems sleep apnea causes are multi-factorial and the other factors are often caused by sleep apnea. High blood pressure and heart disease get blamed for sudden death mid-age, even though sleep apnea underlies the cause of both conditions. If your arches are small, then assume this is a condition which you are already afflicted by. Your older self may not have the option of a surgical fix when it becomes apparent that you need it. CPAP and newer technologies are always options. I don't know your specifics but, you can get it without notable risk up until about age 60. You'll want to be proactive about catching it, get a sleep study every 5 years.
- Jaw joint issues... surgery can prevent them. If you have a high angle occlusion, significant crossbite, or nocturnal bruxism then you should consider surgery sooner than later. I don't know about two decades from now but at this point, TMJ problems are essentially unfixable. An ounce of prevention is worth a pound of cure.
- Same goes for the midface/cheeks. There are no good long term solutions for this problem IMO. And I think that's why most oral surgeons don't want to touch them in conjunction with jaw surgery. We're all really hoping that changes in 10-20 years! And just pray that in the mean time, your starting point is good enough that you can fix your functional problems without uglying yourself too much because that's really what it comes down to more than surgeon skill.