I had a 45 year old, a 53 year old and even a 58 year old in my new hire pilot class at SkyWest. What do they all have in common? They all still fly for SkyWest, love what they do and don’t regret the career change (with exception of the 58 year old dude as he has since retired)
That being said by all means follow your dreams! Even with the industry in its current state, by the time you reach part 121 hiring mins the regionals will likely be hiring again.

Solid advice. Follow your desire. You have 29 years left for airlines. After that there are plenty of solid 135, fractional, and 91 operators to work for. Some 121's even let guys stay on as instructors after retirement.
If you knock out your ratings and keep yourself busy you'll be ready for when hiring resumes.
Good luck.

And if you (anyone reading this) aspire to work at a major, and do not have a 4 year college degree, go knock that out.

FWIW to anyone still asking this question; I recently did just this Pre-Covid at 36. I had spent the previous 5 years slowly obtaining all my ratings (with minimal debt) and got picked up at a 135 operation. As long as you understand the risks and time needed to get back to the QOL & Pay you once had, the only fear is the unknown of jumping into something new and unfamiliar.

Keeping expectations reasonable, doing plenty of research and a healthy savings account will help with the transition.