It's a double whammy for Labour really.
Useless opposition means May and co can set a right wing eurosceptic agenda with no fear of a challenge from the usual source. Because her majesty's opposition now, when it isn't the SNP, is really the eurosceptic wing of the governing party.
So everything has shifted rightwards, and if in times past it was 'un-PC' or irrelevant to diss immigration, now its the exact opposite: anything remotely europhile or pro immigration is, thanks to the referendum, deemed as a crime against the wishes of the 'people' (note even the word 'majority' is not often used)
So Labour's policy on Brexit (support the wishes of the majority but address the concerns of everyone else) is actually quite a sensible one but in the current political climate is seen as dithering or 'all things to all people'
There is no reputable, or respected or feared, voice speaking up