Honestly, I'd be surprised if your winrate was less than 6bb/100 at 10nl and you can expect to be earning more than 3bb/100 at 25nl pretty quickly. If you're smart enough and do a bit of study (tick on both counts) and your mental game is strong, you'll be fine with a modest amount of experience.

It makes me laugh when I see on 2+2 that crushing the game is considered to be 4bb+ at any level. Sure, I think that's the case at 100nl plus, but lower is not the case at all once you've played a few hundred thousand hands and some of your knowledge has become what Jared Tendler refers to as unconcious competence. You'll realise once you get towards the 50nl level and if you dropped back in to 5nl/10nl that double digit win rates are more than possible over a large sample (but obviously there's no point financially). I mean I regularly go on short-term spew sessions where I drop 5BI-10BI in an hour and 25BI in 10k hands and still beat 10nl/25nl for a few bb/100 over a large sample. I don't know what those guys on 2+2 are doing, but they've obviously got huge leaks.