I really wont suggest PoS completely, I would suggest mining + PoS hybrid.
You don't want high interest rates --
Cryptocurrencies are not commodities. It's designed to be spent and a medium to receive payments from. If a cryptocurrency is not that, it's basically a pump and dump scheme.
Actually if you see for a fair cryptocurrency which is not seen as an investment, there should be a little bit inflation, cause that way people will not hold on to it like investment; instead they'll use it to buy investments like shares and gold -- which is something to be seen as an investment.
Proof of stake is not good.
It encourages holding the coins as investment, avoiding it's circulation, i.e. true use as a cryptocurrency. Then worst -- PoS looks at the coin age; the longer you're holding a large amount of cryptocurrency, the higher the chance of mining a block, which further reduces chance of circulation. However if the profits proof of stake is giving you is negligible, then we may nullify this disadvantage.
BUT --
Proof of stake is only a partial measure to 51%.
You need to run a full node in order for the wallet to mine blocks based on PoS and it should be up always; how many people will do that? (especially when the interest rate is low)? When these coins will be made popular, 90% people will run paper wallets giving power to the hands of these 10%; thus an attack may not be that hard to do.
Limited inflation is ideal.
Mining should not die; it should be done to recover from lost coins. After all coins have been mined (in a relatively short period of time), the coins made per unit time should be enough to maintain the prices.
Even real currency have an inflation problem and it's usually more than 0.5%. Actually it depends on the country. But do people have problem with that?
If they did not like their current currency, they always had options. They whould've chosen fossil fuels anytime (who's value will always increase); the reason why they didn't is cause the inflation of national currency is negligible for them cause they use the national currency to spend, rather than invest and hold.
As a way out, I would suggest interest rate of 3% PA using PoS; there will be no coin age for mining, it'll start mining the moment the wallet is in sync and the moment a wallet holds coins; that way it'll preventing holding of the coin as a commodity and people with keep the wallet up to get a handful of coins while they're holding them (as a cryptocurrency). This'll also keep the PoS difficulty up. Cause the interest is not high, we won't have people holding large amounts of coins, but a lot of people keeping their wallets up while they hold the coins.
2% PA inflation will be generated via mining to make a 51% attack still more difficulty.
Inflation is the key to success. This'll make a total of less than 5% PA inflation similar to doge. The way the 5% mined will be kinda unique among all cryptos.
