The importance of this change can’t be understated; this effectively kills compensation at startups in the form of equity, and would make startups completely unable to compete with incumbents. Anyone that has options at a company that grows quickly would be paying tens or hundreds of thousands in taxes to keep their equity, which is still effectively a very risky bet that a company will end up huge. No one would want…
You're right; nobody would want options. So we have to start paying people in actual shares if we want to give equity. Which means you have to give employees way more of the company than deep-pocketed investment bankers who will still invest -- despite their temper tantrums to the contrary -- because there are very few companies that can absorb a nine-to-ten figure investment and do something productive with it.
Just because the system as it exists right now would be destroyed doesn't make this a bad change. The system right now is overly complicated, leads to workers abandoning in-the-money options or staying at a job they hate, and is heavily slanted towards early employees.
But the current model of venture financing is largely dead regardless of whether this change goes through. It's already being replaced by cryptocurrencies / ICOs, which seem like a far more sensible method of issuing restricted stock in excess of the SEC's limitations (since the right crypto / wallet scheme for something like this would not be anonymous). I think ultimately, cryptocurrencies are going to replace RSUs, but the cryptocurrencies that replace RSUs will probably have many of the same governance restrictions as RSUs.
How we treat them for tax purposes is a different problem, but it should make the RSU liquidity problem less troublesome (e.g. you can sell some of your crypto-RSUs back to the company in exchange for ETH/BTC, then convert back to USD and pay your taxes).