Initially I was very sure that both Sanders and Trump would fade quickly - I was wrong on both counts.
Arguably fast growing disenchantment with Clinton (which appears to be a fact) could be propping up Sanders, but it is also undeniable that he has generated some real enthusiasan among Democrats, and Lash represents that pretty well. I suppose Trump is also getting some similar "recoil" support on the Republican side. However, in both cases I have concluded that my intuition may not be so good in the present circumstances. People across the political spectrum appear to be confounding conventional political thought (or at least my own).
I have a very hard time believing the Democrats would put forward an avowed socialist as their candidate, but stranger things have happened.
I earnestly hope that Trump fades and that the Republicans nominate another candidate, who turns out to be successful in the election. There are many choices out there, several I don't much like, but enough good possibilities for that to happen.
The Democrats don't have a lot of time to develop a non Sanders alternative to Hillary. While that lasts the need to prop her up and stay in the race will become ever stronger - a tough situation for them.