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However, the much-awaited Casper update is unlikely to be deployed until mid-2019. Thus, the so-called difficulty bomb is indefinitely postponed and the supply cap for ether remains unknown – factors adding up to high inflation.
Source: https://cryptoslate.com/report-nearly-2-5-billion-paid-annually-to-ethereum-miners-eth-issuance-woes-continue/In the meantime, scalability is not the only problem ETH has.
For example, as mentioned in the article, ETH's inflation rate is almost two times the inflation rate of BTC (and unlike what currently ETH has, the BTC inflation rate is projected to gradually go to zero). A part of the problem with ETH is the fact that there is no supply cap in the Ethereum system.
So if you ask me, I don't know if Casper will solve anything, because PoS is not the ideal consensus mechanism it is advertised to be. But they should certainly give it a try.