If there was no Ethereum Classic, then the Ethereum Foundation's planned transition to Casper will have no big risks. But it is there with a strong development team behind it. If in case Casper does not work as planned what would happen to the platform now? Will the things that were built in it like Augur be ported to Ethereum Classic?
It will not. In my opinion, if that case will be similar with the bitcoin after the bitcoin will have reached maximum supply in the future. I mean the right decision is about the transaction fees to keep the network still usable.
Another question is will the Ethereum Foundation delay the transition? I speculate they will delay it indefinitely because they cannot take that risk. The next question is what other risks are they taking by diffusing the difficulty bomb?
Vitalik has said there was no deadline about the PoS implemented. The next risk it's about the centralized chain, I mean with the difficulty bomb, will make the miner's income will be less a lot. More miners will think to migrate to other coins, More nodes will be shut down and look like the decentralized of the coin will be less.