I don't know of anyone that makes exactly that for a JL, but if you're looking for some soft storage that attaches to a JL here are a few things that Overland Outfitters offers:
This is what they call a Saddlebag. One nice thing about this bag, and all the bags below, is that they zip in place so they can quickly be removed and taken with you:
This next one they call a Zip & Go bag, it's seen here in a LJU but they are also featured in the Quadratec 30th Anniversary YJL show Jeep:
And this one zips to the back of the seat just like the Zip & Go bag, but it's larger, they call it the Backpack Messenger Bag:
All of the above are made from military grade canvas with real leather accents and reinforcements and they all come in black as well.
I can talk to my contact at OO to see if they might be interested in producing the type of Saddlebag you posted about but I don't know how much general interest there might be in that type of bag - I almost never see them on Jeeps in the wild.