Barry Barish of Caltech heads the Global Design Effort (GDE) for the International Linear Collider (ILC). As anyone who has followed the news since December 2007, the ILC has had two major, and possibly fatal blow to its plan: the UK pull-out and the drastic reduction in funding in the US.
This is a good article on Barish and his effort within the GDE, including his take on the future of the ILC. I think most people kinda agree that even if the ILC gets built, it will probably be the last of its kind because the cost to go beyond that is no longer realistic. Unless new acceleration schemes that are currently still in basic, fundamental research stages (such as plasma wakefield, etc.), particle accelerator for high energy physics will probably not get any bigger than the ILC-like design.