I think there's some room to experiment with various options as
extensions, in beta, etc. The "pick something" stage is going to have
to weigh a lot of competing objectives -- for UI building, for content
templates, for scripting, visual editor support, etc. I don't see us
getting to the "pick something" stage until a number of different
implementations have been prototyped in different contexts.
--scott
ps. Tyler: please play with the 'spacebars' implementation in
https://www.meteor.com/ ; escaping can really be transparently correct
if your implementation works with structured HTML, not just banging
together raw strings.