Candidates in future elections may try to adopt bernie's stances
But really, Clinton already has.
If Sanders had been running independent and had challenged Clinton as much as he currently is, would you still consider casting an independent vote useless?
Now, you're right; mindless drones will vote along party lines, but that's less a failure of a two party system as it is a failure of morons being allowed to vote based off whatever they see on CNN and Fox.
Let me give you an example.
Prior to my employment as best NA cRPG admin (sit the fuck down, Artyem), I was a campaign director for a Green Party guy in Saint Louis, MO.
A good number of folks I spoke to were avid supporters of the currently seated Democrat, although a fair portion shared their concerns about both her policies and length of term.
We managed to get our guy 30% of the vote (which was absolutely remarkable in St. Louis politics and US politics in general, for that matter), and we're hoping to see a trend.
It showed the establishment that people were upset, and that they had an actual chance at losing their power.
Did they lose it? No. No they didn't. But the Green Party paved the way for future campaigns, and they took a little power away from the mainstream Democrats in the process.
That, good sir, is a victory. Not the victory we hoped for, but a victory nonetheless.