The two wikipedia articles below have an easily searchable summary of both the Airport and 802.11 timelines in the past:
Looking specifically at 802.11n - Apple shipped product in November 2006 supporting the draft in MacBook Pro cards. The AirPort hardware followed in January 2007 and the standard didn't get published until October 2009.
Apple clearly isn't allergic to getting way ahead of a standard, and often builds the flexibility to roll out new standards in shipping product and will never mention it (and sometimes the people disassembling the hardware when it's released are in the dark as to these undocumented abilities).
Historically, if a protocol were ready for robust service this summer, you would be safe to presume Apple has considered and built for that more than 18 months ago.
The real problem with these sort of "crystal ball" extrapolations is that Apple only backs things it knows will be a long term success. Take for example Blue Ray and HD DVD. Those standards are clearly far superior to DVD, yet Apple skipped those and has never spent time or money putting those faster, better, and more data dense formats into production. Clearly fast networking is more core to computing and a desirable competitive edge for marketing hardware than an optical media format choice, but you'll want to carefully examine how any "advancement" fits into the big picture for consumers and/or businesses.
I personally don't see large percentages of the consumer population needing faster Wireless network access than 802.11n since fiber to the door and the rest of the network infrastructure in the US is lagging what current AirPort hardware can deliver. I would look instead for smarter devices that proxy app store downloads and undercut various cloud storage services with an Apple solution in the coming months rather than a spec bump.
Apple clearly has the money and expertise to skate to where the puck is going to be in terms of Wi-Fi improvements, but we as consumers often don't have the perspective Apple's engineers have of what's really in the queue for technology so our guessing is more of a parlor game than something I'd plan a purchase or investment around.