Yea, I see this guy as more of a help for Valakut in Legacy than doing anything in Vintage.
Unless someone wants to make U/B Realmwright/Scapeshift combo in Vintage.
I think it's fair to assume that Moxen are superior to land ramp. Reliance on a particular 4 cmc sorcery is also questionable.
There's an issue in that you need a blue source in order to make your lands tap for blue. It doesn't help you to cast Ancestral, Time Walk, etc, since casting this shares the same prerequisite as casting those. There's an exception for Cavern, but that just makes blue power more likely to be dead than running Islands instead.
At the same time, Cavern will allow some number of uncounterable Lodestone Golems.
Again, that increases the odds of stranding an Ancestral in your hand. Brown's draw engine is the mulligan.