A contingency if windows 8 fails, can't be windows , unless 7.5 remains as a low cost option.
When the MS deal was announced, and despite the "no plan b" comments by e-flop then, I drew people to the fine print in the Media release, that clearly stated the deal did not exclude Nokia from further developing or using other options, and that the deal was subject to market and financial exclusions.
Harmattan as a high end option could still easily be on the table, and would sit nicely on bigger screens and faster SoC's that already exist in the Lumia line-up.
time will tell......