Oslo could easily fit in a Broadway house, no question. Like any play at the Mitzi Newhouse, it takes advantage of space- specifically its flexible seating configuration and its entrances in the seating area- but that can be easily modified for a Broadway run (Vanya and Sonia and Masha and Spike did so). It's basically a unit set with actors sliding furniture on and off.
I think it's a fabulous, well-acted, and timely play that would be worthy of Broadway run. Whether that's actually in the cards is a different matter.
"...everyone finally shut up, and the audience could enjoy the beginning of the Anatevka Pogram in peace."