Sorry, but you guys are living in dreamland. First of all, reverting to a DSLR is not a viable alternative for most of us (who aren't already using one and wish to stick with a single system). There's the weight and portability issue, the additional cost of the camera, and the need to haul both systems around in many cases. I don't see this as any sort of a viable alternative for most photographers who aren't already toting around all that equioment.
Fuji has a long history of building real quality glass and pricing it at a premium. If you believe that they would undercut Canon's price for the similar 100-400L lens, which is aging but still a very good quality and viable alternative for Canon users, you're kidding yourselves. IMHO, $1,500 is remotely possible, $2K is a lot more likely. Better to look towards Canon (100-400) and Nikon (80-400) as a more likely basis for comparison.
I'd really love to be dead wrong on this, but I can almost guarantee that you're way undercutting what Fuji will likely ask for this lens. Unless it's over the top crazy expensive, I'm in regardless and my 7D plus 100-400 go on the block.
Let's see what we have on the market today.
Canon EF 100-400mm f/4.5-5.6L IS USM: 1699
Sigma 50-500mm f/4.5-6.3: $1,509
Sigma 120-400mm f/4.5-5.6: $919
Sigma 150-500mm f/5-6.3: $869
Tamron SP 150-600mm f/5-6.3: $1069
Tokina 80-400/4.5-5.6: $719
All of those are FF lenses and some of them are also longer, so 140-400 APS-C should be much cheaper to manufacture.
Based on the market participants today the Fuji lens shouldn'tr be more expensive than $1000. Taking into account that Fuji regularly marks up their prices compared to competition, I would expect them to set an MAP in $1200-1500 range and later offer promotions bringing the price closer to $1k. Above $1,500 there will be very little interest, the DSLRs with a long telephoto lens may look a lot more attractive.