I'd be curious to hear thoughts on the following:
-What would be the optimum sizes for ink jet papers?
-Should it be exclusively metric?
-Should it be exact to say a 35mm DSLR of 24mm x 36mm, or should the paper size still force some kind of crop?
Relying on a forum like LL will give a very poor understanding on what the market requires. You will get personal requests which might or might not be representative of professional fine art landscape photographers - in any case a minuscule market segment. Even if Michael would run a poll it would only be representative of the people who actually bother to respond to polls, not of the wider LL forum membership, let alone your target market.
The obvious route would be to go to IDC or Gartner (or whoever does market research for photography gear), get market shares of sensors and cameras, installed base, and printing rates of each, and utilize that data. Then take a closer look at the size requirements - eg. 3:2 DSLR guys print larger, while 4:3 MFT guys print smaller. If 3:2 sensor users print 100m pages a year and 4:3 sensor users print 45m, that should give guidance on which paper sizes and aspect ratios to launch. Look at your existing paper sizes and see where there might be room for a new paper - this is where recommendations and personal requests found on forums like this will actually be handy, as they can give you hints as to where the gaps are. If someone requests 10x57" paper but there's no 10/57 ratio sensor out there, it's probably an outlier
Many (most?) paper sizes should fit existing printer widths. The influence of existing frame, photo album and portfolio conventions should not be ignored - there are still a lot of people who religiously crop to legacy aspect ratios. And as I said earlier, a big hurdle for adoption of a new paper size is that it costs money to hold stock at retail, so an attractive marketing campaign, rebates, samples, return program etc. is probably necessary.
The bill is in the mail