And I, and many others, hope they don't. Google I/O became a "why not" conference to go to for those in the area because the freebies outweighed the cost, and it is ridiculous that Google starts to grandfather that in.
But there is a presale aimed at exactly this group.
They've had the "I/ON" group (aka "loyal since 2008") since 2010, if I remember correctly. There was no presale but it also took 90 days for the 2010 conference to sell out, so it wasn't like you needed one. The 2010 I/ON group got priority seating at the keynote, a different T-shirt, and some other trinkets.
In 2011 they did presale for I/ONs two weeks prior to general registration, and a presale for other 2010 attendees one week prior to open registration (and only for attendees who paid full price in 2010, not academic discounted tickets).
2012 had just a presale for I/ONs, no early registration at all for 2011 attendees.