It's not totally clear how the IQ/Index ranges will change, as they don't appear to have released that information yet, but there have been efforts made to strengthen the subtest floors and ceilings, which can only be to the good, in the event that extended norms are developed. Keeping scores in perspective, if you read the WISC-IV Technical Report #7, which has the extended norms in it, you'll note that exactly one child in 2,200 members of the standardization sample obtained a GAI of 151, and none obtained an FSIQ of 150+. So from a general utility standpoint, there is no particular value in going above 160 on the FSIQ chart, but maybe the stronger subtest ceilings will allow for a better extended norm chart.
