I finally saw an image of a 2500 flowcell so you can stop looking at the one I mocked up based on discussions with Illumina personnel just before AGBT.
One thing immediately struck me and that was how much a HiSeq 2500 flowcell looks like an old fashioned razor blade? OK, you may have to squint to see the similarity!
Why then does a HiSeq 2500 cost $700,000?
PS: I can't be the only person looking forward to real "genomes-in-a-day"? 20x coverage is for wimps! ;-)