...and in the process, dropping salaries which FI's can expect, as every T,D and H will go and do an FI rating. Maybe?
Certainly hope that this would not happen. I think the numbers would be fairly small - it's still a big enough commitment and your average PPL is unlikely to make it. And there certainly is a considerable shortage of instructors! I'd certainly instruct if I could but at 57 years old there's no way I can justify the enormous expenditure in both time and effort to do the CPL exams.