Hi LE. My husband is a physical therapist, he graduated PT school when He was 32. He says he was the second or third oldest in his class, so yes, most of the other students were like fresh out of undergrad.
Yes nowadays it is a doctoral program, what you get is a DPT or Doctor of Physical Therapy. (Impressive sounding but they dont get to go by "Doctor") My husbands program was a 3 year program, and he took at least a year to even be able to apply by taking some prerequisite courses that you have to have to apply. It was a rough 3 years in our family, there was a LOT of studying. And near the end a lot of practicuum hours (fieldwork or internship) where you work for free AND continue with classes and studies. My husband could not have even a part time job while he was in PT school. He was still able to participate in most family activities and help out with the kids (just one back then) but boy did studying overtake our house. I do not miss those days.
I would heavily weigh how long it would take to be application-ready (how many pre-reqs do you need to get, where and how will you get them) when you could start a program and what age you'd be when you were done, vs. what age you'd plan to retire, and how long you'd think it would take to pay off the loans.
I would advise to find the cheapest program possible at a cal state school if you can.
My husband went to azusa pacific for PT school and while a lovely program, it was a private school and very expensive. It'll be about 10 years til we pay off the loans and we are paying them back pretty aggressively, like 12k a year. If you think you will still be working by the time you finish paying off the schooling it took to get you there, so you can enjoy a few years of JUST enjoying your paycheck and not paying your loans, then I think it may be worth it for you if you think its your dream. Why not follow it.
For me, I want to be done paying off our own school loans just in time to pay for my kid's college... Sigh.
The good news is, there are tons of jobs for PT's and a variety of places you can work. So far my husband has gone from rehab in a hospital setting, to working with special needs kids for a school district. So once you get out and in the workforce, its all good. Feel free to PM me more questions, I can always ask my husband.