No idea. It's so hard to find information on and no one, especially the valley rags are interested in reporting on it. I'm curious as to why the community thinks that is.
The chances of it getting through within the next few years, is 100%, in my opinion. There will be numerous opportunities to fix this particular problem, along with all the other items getting targeted when it comes to tax & regulation reform. It has wide bi-partisan support, and the tech industry is the largest lobbyist force on earth now, as such it'll be a matter of how soon rather than if.
One counter point... think about who is lobbying for changes. If it's primarily founders/executives at startups, know they do not stand to gain from removing these golden handcuffs. This bill will make turnover higher and hiring more expensive.
It's a double-edged sword. It also means that it will be easier to hire people away from the start-ups. Google/Facebook/Amazon, even Oracle, must be getting a lot of "nos" from start-up people who'd be interested, but are going to hold out for a year or two more (and who aren't quite valuable enough to buy out).