Spent a couple of hours fruitlessly tinkering with CAPIE and average thickness, trying to see if anything interesting turned up.
Mostly not, and not really worth posting charts. The TL;DR is, the end of season thickness has remained relatively constant for most of the last 15 years, dropping slightly on average to about 1.75M.
The "start of season" average thickness has dropped pretty dramatically, now at around 3-3.5M
Neither of these unfortunately tell us much of anything except they are derivative of changes in area and volume, for which they are the ratio, and in spite of widely changing ranges of area, have stayed pretty surprisingly constant - +/- about .25M - over the last 10-15 years.
My take away is that average thickness will probably remain pretty much the same at the end of season until we blow out completely (as in sub 1,000,000KM2). But then, oddly, the average thickness at end of season may go UP, as a higher proportion of the surviving ice may consist of stuff calving off of glaciers in the CAA and Greenland.