I don’t see him ditching Pence, and no one bar a few Bernie bros care about Gabbard.
She has also recently said that she doesn’t believe that Trump is not guilty (she said that the reason she didn’t vote about his impeachment was cause the impeachment was done in a partisan manner, not cause she thinks that Trump is innocent).
It hasn’t happened recently and it is not going to happen. There won’t be a Republican/Democrat ticket or vice versa.
I'm not suggesting that Gabbard would run with him as a purple ticket, I'm saying that she could switch parties and run with him as a born again Republican.
Just look at her voting history. I'm struggling to find a position that contradicts Trump. Beyond the impeachment votes she's abstained from votes condemning or sanctioning Russia, Turkey, China and Saudi Arabia, abstained on advancing voter rights, abstained on a vote for women veterans rights to health care and abstained on a vote for lower drug costs.
It's really not beyond the realms of possibility that Trump might view her as the perfect running mate, especially if she is prepared to get down in the dirt and spew bullshit about how corrupt Democrats are behind the scenes.