They're not going anywhere, these people you're talking about eschew SJW'dom and therefore won't be the establishment's preferred demographic, nor will they get the money and support that SJWs receive.
They're also too disorganized and prone to disagreement due to the fact of their hipstery nature and their faux dedication to "critical thinking" which is just basically being a pretentious contrarian.
The "old left" doesn't exist anymore and hasn't for a while, you have the piece of shit SJW globalists, and you have these neo-rationalist-lefties who couldn't organize a baseball game much less assemble support for and mount a bid to bring a candidate into the white house.
These fucking people have nothing that moneyed arch criminal elites are looking for, they'd literally have to co-opt some SJW causes and package them with a neo-rationalist twist and hope people will fucking buy into it (they fucking won't).
Think about it, what are if any issues that these cunts can repackage that aren't easily identifiable with the SJW left or some other school of idiotic socialism? There's NOTHING, nothing at all, they'll only be able to try and swathe it in rhetoric that seems "hip", but doesn't ultimately mean anything new or meaningful at all.
So guess who they'll be taking their support from? Will it be the right? NOOO, it will be from other factions of the left, that's why this is so fucking beautiful. These people you're describing will be desperate to define themselves and it simply won't be fucking possible. The only thing they could do is encroach upon center-right territory, but then they'd lose everyone if they picked upon shitty economic policy or signalled against gun ownership or something.
These people you're speaking of, they're fucking BONED, just like the SJW left, they're totally fucking boned, they don't have the numbers on their own, and they won't side with the SJWs out of utility because they know SJW politics are fucking finished.
This is all so glorious guys, you have no idea, they're fucked, they're so fucked it's not even funny.