I was hired at SkyWest in early 2007 with zero airline experience at 44 y.o. It's not very likely from that point to make widebody US major airline captain.

But, there are plenty of other opportunities in the world, if you're willing to move (a long way) from home. For example, Emirates is hiring, with an age 48 year maximum, if you were to be hired there, you'd probably be a heavy captain by age 58.

Of course, Emirates is not an entry level job, much like any US major carrier. I'm confident that you probably know that world wide, the typical age for mandatory retirement from flying is 65.