What's the reason that it wouldn't be viable after raising the block size limit?
nobody would use it because people won't buy new HD's just to run gavincoin
Increasing the block size limit by a factor of 20 does not increase the size of the blockchain by the same factor! The chain will grow gradually over time.
Besides, the average cost per GB now is 0.03$. Storage is the cheapest system upgrade that one can get.