5 years, yeah probably. But here's the thing, isn't ASF a microsoft codec? Say you're using Linux in 5 years, or want to play the file on your friend's Mac in 5 years...then what? MPEG's gonna outlive us all, for better or worse. DIVX has a following which has reached a certain mass and will probably continue, how long is measured in computer time of course.
I really don't know what to tell you though, MPEG is gonna cost you a lot more storage space to get the same quality as compared to DIVX...and probably as compared to ASF as well. Upside of course is if you make the mpegs to VCD specs and burn them as VCDs you can play them in a DVD player from now until the day you croak. Who knows if ASF, DIVX, ETC will ever (or which ones) work in a home player the same way.
--Mc