I don't know if the J-red 670 counts as a 60cc (or so) model (pretty much same saw as 266/268xp), but I think that size was just about perfect for most needs in my area. Once in a great while a guy could get into really big timber requiring bigger than 20" bar here, almost never. I replaced a J-red 70-E with the 670 and never looked back.
I took a regular job in town, quit cutting down as many trees, and siezed the old 670 a couple of years ago; I lucked into a 625 at a farm auction; 60 cc's and not as much raw power as the 670, but a more forgiving powerband. I liked it almost as well as the 670. Now that 670 runs again, I have more choices, but I'd be sad to think that there were no more choices in this range.
In my opinion, the 575 is the first of the next generation, just like the 61 was a while back. Soon enough, the 575 will be yesterday's news, just like the 61 was; the extra weight in a 75cc saw will feel just fine in an 80cc model.
The 154/254/357/359 series is closing in on sunset; I'd say that the 545 series will have a "pro" model or two based upon its chassis, maybe up over 60cc. I think it's a pig at 13#, compared to the 357/359, but it is marketed right now as a 55 replacement.
Others will say that Elux and Stihl have seen the handwriting on the wall; the market for quality saws has come and gone. Maybe so; the pro will soon be stuck with either last year's saws, or last year's designs. maybe that's allright; aftermarket parts for certain models will soon become lucrative enough that prices will drop; keeping that old 372 or 044 in fresh cylinders and pistons may be an atractive alternative to buying the latest consumer clunker. Many dealers make more money on parts and service; don't look for them to kick too much!