I'm not opposed to this, except that I think it would be unfortunate if we got into a mode of voting on things, rather than working to near-unanimous consensus wherever possible.
Sometimes there will be really irreconcilable difference of opinion, and then I would say that a vote isn't a bad idea, but of course subject to the caveat that a vote would only be advisory. For example, I couldn't respect a vote to abandon free licensing, or a vote to turn Wikipedia into a anti-copyright-protest site, etc.
But usually, differences of opinion will not be irreconcilable. A modified proposal might satisfy everyone.
For now, I propose that we respect Larry's decision to do away subpages in the new software, and that we test the new software on meta.wikipedia.com, which will be the newly appointed place for policy discussions and general commentary. (/Talk still belongs on the main site, of course.)
If we use that for a month or so, we'll all probably have a different perspective, grounded in experience rather than speculation, of at least some of the aspets of no-sub-pages.
I'm betting that consensus will grow out of that.