probably yes - as far as I know they're implementing Casper in the Serenity release and they will switch to Proof-of-Stake this year, but don't quote me on that. But of curse you can still participate in the consensus-process as a validator and gain some ether as reward, it just works differently.
Depends on how much you want to spend and the risk that you're willing to take. If you think Casper will be postponed (which it already has once), then you get more time to mine and reap the rewards. However, as @Demetori mentioned, the Ethereum platform will perform a hard fork to implement a new PoS system soon. Some online links mention Nov 2017 by the latest.
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But of curse you can still participate in the consensus-process as a validator and gain some ether as reward, it just works differently.