As they always say, "high risk, high reward". There are many "De-Fi" tokens and PoS coins which offer high rates, but they're subject to the negative effects of inflation. It's why I believe that coins with low stake rates will be able to last for long. ETH could be worth staking if rewards remain relatively stable. My concern is that ETH will experience a greater level of centralization once it becomes a full-fledged PoS cryptocurrency. Imagine a huge exchange like Binance or Huobi staking most of ETH's supply. It'll bring centralization to the Blockchain as we speak. Consider what happened with the Steem/HIVE fiasco where Binance controlled a large supply of tokens on the Blockchain. They've decided to support the STEEM blockchain's new hard fork, effectively putting user's funds at risk (the controversial fork revoked access to some users' funds on the Blockchain). It could be disastrous for ETH if a huge player like Binance controls most of the coin's supply.

All in all, it seems to me that there's no other solution for scalability other than making ETH a full-fledged PoS cryptocurrency. For those who still love a mineable smart contract platform, Ethereum Classic is an option to consider. I'm guessing that most (if not all) ETH's current miners will switch to the ETC chain once it becomes a PoS coin. ETC will become much stronger, and decentralized as a result. ETH will become less decentralized, but its performance will increase towards new heights. Staking ETH now might be wise, as it could reach new ATHs in price due to the "De-Fi" hype. Who knows if ETH hits $5k after the upgrade? Just my thoughts