You should be fine. The dinosaurs (I'm just about there) will be moving on to other pastures at a rapid rate. Any major will be a great job, don't limit yourself. It's a crapshoot getting to one. Just ask anyone 55 or older that's flying for nonsched or regional airlines. Not everyone gets the right breaks to make it. I consider myself fortunate to be where I am, although I worked very hard to put myself into position.
Take a flying job that you will enjoy. CFI for 1500 hours is boring. Go fly freight, aerial photography, charter, anything to give you real world, outside the pattern experience. Once you get your 1500 hours look at something other than a regional. Pic for Ameriflight at 1600 hours is better than f/o for a regional without a guaranteed flow.
And flying for an ACMI carrier like Atlas or Kalitta will give you some great experience and cool stories. I just flew with a F/O who was a captain at North American while he was on furlough. He had a blast. The job can be fun if you go to the right places and enjoy your time.
Just don't marry the first f/a you shack up with. You need to be able to move without family or spouse obligations for a while while you get started in the business. I didn't do that and it cost me two marriages until I got settled. There is a huge time obligation that goes along with this job, many spouses don't get it. Those that do are like gold.