Use of Futures/Promises in CSS Font Face APIs

During today's presentation of an alternative API for CSS FontLoader,
reference was made to so-called "Futures" or "Promises". I would like to
know:

(1) what material improvement is afforded to this alternative when compared
with the existing (non-Futures) API proposal? that is, what new or
different behavior or functionality is offered by using "Futures"?

(2) where is the formal definition of a Futures API or functionality that
would become a normative dependency were the "Futures" version of the
FontLoader API adopted?

(3) what other W3C APIs under active development (or complete) makes use of
said "Futures" APIs?

(4) does the proposed use of Futures create a dependency on a newer version
of ECMAScript than is currently assumed by HTML (which is 5.1)?

(5) what is the expected impact on schedule for reaching a FPWD (or LC) if
this alternative "Futures" approach is followed?