how is it even possible to have thousands of spvp SC's when there are not enough resources to MM all of them? and even then, they're not secure.
Note that Bitcoin itself could be supported with one CPU miner provided that it is not attacked.
As I've mentioned before, trying to out-run the threat of potential mining attack is as futile as a hamster running on a wheel. Successful sidechains will almost certainly need to evolve other protection modes than simplistic gross sha256 hashing power. The best hope for Bitcoin to mitigate the inevitable reality that mining becomes unprofitable is that sidechains offer money-making opportunities for miners which are more lucrative than attacking Bitcoin itself.