Bottom line, if you push hard you could be at a major airline before age 50. With projected retirements you would probably have the opportunity to upgrade within 5 years, or you could hang out in the right seat if you prefer seniority and QOL over money.

You could facilitate this by doing as much flight training in the year before you retire...I would in fact highly recommend this, you want to make sure you actually like flying. You can get a PPL and likely an IR in one year of evening/weekend flying if you trained a lot.

Due to your age and the mass industry retirements speed is of essence, so I would go for fast track training rather than trying to save money. If you're going to do this, debt would be better than delay considering age and seniority progression.

You'll need a clean criminal and social-media history, ideally an undergrad GPA of 3.0+, and will want to avoid failing any checkrides (especially part 121 or 135 rides). For part 91 and 135 training, do your homework...some schools and 135 operators have poor consistency with training success, you'll want avoid those places if at all possible. A master's degree will help for most majors.

A plan B might be a regional "career", but I use quotes because the viability of the regional industry will be in serious doubt as pilot hiring ramps up and you can probably make as much just by staying at your current job. If you're going to do it, shoot for the majors but be prepared to stay at a regional just in case.