The second review of "SE-0095: Replace protocol<P1,P2> syntax with P1 & P2 syntax" ran from June 22...27, 2016. The proposal has been *accepted*:
This syntax has been extensively discussed by the community, and is a cornerstone of the “generalized existentials” work for future Swift releases. The community was overall positive on the feature with a few subjective concerns about “&" being tightly associated with bitwise logical operations. The core team believes this will not be contextually confusing since it appears in a type position, between two names that are obviously nominal types (e.g. they are capitalized).
I filed SR-1938 to track implementation of this work, this is a somewhat advanced starter project which would be a great place for someone to dive into the parsing logic in Swift.
Thank you to Adrian Zubarev and Austin Zheng for driving this forward!