The answer is simple : 3rd party firmware for drives!
This has been done for many things in the past, now it is time for some folks to write/re-write firmware/microcode for the drives. Not all drives, say 1TB and up drives, the popular and cheap models.
There are really no physical limits, the drive makers make the FW so we can;t easily use the drives in arrays, so we have to spend more just for a drive with a few 1's and 0' in the FW that don;t make the RAID controllers kick them out of the array.
Option #2: The 1st person to make a RAID controller, either software or hardware, that can account and compensate for TLER or whatever it is being called, will do well for a period of time.
I once took some 750GB Dekstop drives and flashed the Enterprise firmware, and guess what? The array ran w/o drive failure for 15 months, not bad considering before the flash I had to rebuild every other month? Same drive, just a flash fixed me up just fine.