Granted that witnesses are weighed and not counted, I would be *extremely* surprised if R7RS-large had a One True Keyword Style fully integrated with lambda. I certainly don't intend to put any such thing up for a vote unless someone appeals against the chair. SRFI 177 is a real possibility, especially if case-lambda and/or explicit renaming make it in.
Of course, there's nothing to prevent you from renaming standard lambda out of the way and using keyword-lambda as lambda, at least in principle, though using import to mess with the names of fundamental syntax forms is going to be problematic. And plain application has no syntax keyword, except in Racket where it's #%app (ugh).