Bill Gorman at TVbytheNumbers.com has an interesting analysis of which shows are likely to be renewed by NBC, asking how the overall ratings problems of NBC will affect the renewal chances of "Chuck" and "Heroes."
Gorman writes, "Neither ‘Chuck’s’ nor "Heroes’" spring new episode ratings averages are anything to be proud of, but NBC has been crushed so completely, that through May 2, ‘Chuck’s’ new episode ratings average was still 96% of the network’s new episode scripted average as a whole. ‘Heroes’ ‘relative spring average was lower (85%), but not down in the scary ‘Mercy’/’Trauma’ range (61%). Because of that, I think what hope remains for both shows is that they’re used as replacement show ratings crutches by NBC in its feeble state. No combination of their renewal or cancellation would surprise me at this point."