It's a simple matter of treating them properly. Particularly, do not ever wash them in hot water and also do not ever put them through the dryer on hot either. Heat is what ultimately destroys elastic (differ to your underwear bands) so actually, avoid warm too... and hang it up to air dry instead. A couple times won't do damage, but washing and drying them in hot ALL of the time absolutely will. Also keep it hung up, not tossed on the floor. Simple things like that will go a long way. Oh right, if you like to swim... designate ONE for that because the chlorine/salt will ultimately make it useless (especially if you don't promptly wash it out after the fact).
Otherwise, you should not have any problems. Then again, note that because of their design, the 983 and 997 will both wear out quicker than the others (<998 etc). Their extra layers are only on the front, but in the back they have an even thinner and therefore weaker mesh kind of panel. That is the one taking all of the strain from the front layers... "an object is only as strong as it's weakest point". Basically, you're better off avoiding those if you really want longevity. IMHO, the initial extra binding power is not worth it when ultimately they will wear out worse.
The goal is not to get "totally flat", but to get the pectoral look. It doesn't often take "extreme" to get there, really. Case in point my 974 still does the job after five years (although I am presently planning on two new 998's soon. I just hope I can get over the new 'improved' changes they made though... the new seams IMO are hellish. They should have left well and good enough alone, not trying to 'fix' what wasn't broken. Oh well).