There is a practical limit to how far a wheel can be dished so, although SpongeDad may be right, something has to give. In other words, either the old (but improved) Spinergy carbon bladed wheel might be reintroduced or a frame with a tandem-style 145mm dropout spacing which will accommodate a low-dish wheel and a 12 cog cluster.
Cogs might have to get thinner and thinner so we will end up having to go to a jewelry store to buy a chain! When will it end?