Too much time: polls mislead voters

Generic polls shows that Republicans have an edge. It could be bad news for Democrats.
But how realistic or relevant is this information?

Take a Democratic firm PPP

Republicans 45
Democrats 41

Looks bad right?

But this assumes as of today:

Republicans will win 16% of black votes come election.
In 2006 they won 10% in a pre-Obama era.

Republicans will win 40% of Latino votes come election.
In 2006 they won 30% in a pre-Sotomayor era.

Add to this months of targeted advertising in a normal campaign and things while not looking great for Democrats, certainly don't look horrible.

Right now there's not much for political junkies to do so they write what they can. But Democrats shouldn't accept conventional wisdom as something real in this case.