Flying is not dead and there is a 100% chance you can come back and fly... Only you'll need to do it at a percentage of what you were getting paid before.. and yes you can go fly 777s, if you're willing to give up any quality of life as you know it, just to climb the seat ladder..
If you don't mind giving up Christmas and Thanksgiving with your family for a long time to come so you can keep jumping seats, just to wait until you're in your mid 50s to command a 777, you can do it..
You may have a better quality of life if you just lose the big jet concept and enjoying flying somewhere, where you can just build a life and some seniority. It's a personal choice... the big iron jobs are still there, but the chances of doing it with a legacy US carrier have become VERY rare.. The guys who will fly the big iron here for the US carriers in our lifetime, are already there working now. The change of the business model over to the regional jet, has made flying for a high paying major an exception, not the norm..
Those jobs will be there in the form of World Air, Kalitta, Atlas..etc.. You'll just have to do it at single isle/narrow body pay scales, because that's what we as a pilot group have come to accept and some else will always take the job.. so we hurt ourselves.