I used to really, really want it to be canon but post timeskip Lance and Keith are even further in maturity level. I was hoping they'd get to grow together but now it's like. An angry chihuahua screaming at a full grown tiger haha.

I think there is some suggestion he'll talk to Shiro about being bi. People like to bring up S1E1:

Hunk: Can you keep this thing straight? Lance: Relax I'm just getting a feel for the stick.

And the planet he took Nyma to had a palette similar to the bi flag.

It'a a tossup whether they'll go for it tbh. Klance is the same just because it's a big part of their fanbase and Korrasami happened in the last few eps iirc. So it could be similar structuring. They're probably finished with all the writing and storyboarding so I'm carefully watching their reactions in interviews with regard to questions like this haha.