Getty Images Vitalik Buterin during TechCrunch Disrupt in London.Sure, coming from any number of bitcoin BTCUSD, -0.69% critics, those comments would be expected. But coming from the guy who invented the second most valuable crypto before he even turned 20 years old? Vitalik Buterin, Ethereum’s co-founder, recently told developers that he’s “concerned a lot of these token models aren’t going to be sustainable,” according to Bloomberg. Buterin is concerned about supply. Where bitcoin has a 21 million coil limit, there’s no scarcity to support Ethereum prices, which are still managing to take out new highs. Regardless, he says he might do something to change that. Specifically, Buterin says he’s interested in the idea of imposing fees, known as “sinks,” on applications built atop Ethereum. They would limit supply by destroying, or “burning,” ether tokens over time. “Introducing some kind of sinks into Ethereum is definitely something we’re looking at,” he said. Buterin also spoke of another way to limit supply. The proof-of-stake plan, which may be put into place as early as the end of the year, rewards users for locking up some of their ether for a set amount of time, Bloomberg reported. Meanwhile, Ethereum saw its price recover a bit on Wednesday, after a coding error resulted in the freezing up of almost $300 million worth of coins.via