Should we also backport this to 3.7?

Hm, actually there was an old test checking that x: tuple = 1, 2 fails with syntax error. So maybe it was actually a conscious decision to prohibit this. I don't remember. Anyway, I don't have a strong preference here, so @gvanrossum @rhettinger I leave the decision up to you.

OK, after more careful reading of PEP 526, I found this:

Only single assignment targets and single right hand side values are allowed.

So it was a deliberate decision. The PEP is final now, so I would propose to just close this, unles @rhettinger really thinks we need to allow omitting parentheses.

This was meant to guard against interpretations like

var1: type = 1, var2 = 2

Sorry, too soon.

I think that worry was unneeded and agree with Raymond.

We can change it in 3.8 but no backport.

This was meant to guard against interpretations like var1: type = 1, var2 = 2

I think it would make sense to add a tests that this particular code still fails.