Realistically, a drive should last you at least 3 years of moderate use, under good conditions. In most cases it will be more then this I believe, and in some circumstances it will be less then this. Sometimes drives are deffective, and sometimes drives get dirty and gummed up, and this can cause premature failure. A good drive might last you 10 years if properly kept up! I know Yamaha has made some pretty awsome drives in the past, even some of their very first drives to come out have been known to still be in operation for some people!
It's too bad you can't bring your burner in for a "tune up" though
Punch Cards -> Paper Tape -> Tape Drive -> 8" Floppy Diskette -> 5 1/4" Floppy Diskette -> 3 1/2" "Flippy" Diskette -> CD-R -> DVD±R -> BD-R
The Progression of Computer Media