Odds of Hanging On
If you make it to the Majors, give yourself a pat on the back. You're probably going to stay in the Majors for a while. With playoff games setting ratings records, people still really like baseball. Your job's not really going anywhere, so as long as your knees, back, and dignity can take the stress, you've got a lifetime of innings ahead of you.
If you don't make it to the Majors, but you're still satisfied with your career, give yourself a pat on the back. It's tough to succeed in a field with low pay, a stressful lifestyle, and a great view of other people doing the same thing but for way more money. If umpiring's really your thing, though, you won't mind any of that.