No! lol Even though this would be a neat experience on the new Mac it would ultimately mean a step backwards into vendor coding. Being that the top bar is brand new (and thus its success is not yet certain) I think time could/should be spent elsewhere. For example, more controls/gesture events for full touch screens. :)
@mgiambanco "others are already doing it so is this any different"? No, it's not any different and that's precisely why it shouldn't be done. We are trying to get rid of vendor-specific code so that engineers have to rewrite feature code as little as possible to suit each vendor platform. (See HTML5, CSS3, Responsive Design) This might be feasible for Browsers like Safari to support, e.g., by placing a copy of the <nav /> in the Touchbar. But I don't see any real benefit of creating an entire, vendor Web API just to support this hardware feature that is likely transitory anyway.