I've been brainstorming on this low end case...
I called a local camera store and found that WA and Fisheye lens hoods were removable but he didn't have anything in stock so i could not get a assembled height comparison between the 16+Fisheye compared to the stock lens.
If the combined height was close enough to fit in this case that might give some really compelling beginner level CFWA capabilities 
This would be such a hot casual shooter setup. (someone who has to get on a plane for a minimum of 2 hours to dive or taking pics around pools or local lakes without worrying about the oops factor)
A high level comparison:
Casual / beginner - NEX 5n camera +16mm + fisheye +case = $1100.
Low/Mid Range UW - EPL-3 @ $2650 (Camera + WA lens + Zen dome + Case)
Low end DSLR - T2i / Nautica @ 4700 (T2i, 10-15 Tokina + compact zen dome)
Cons , lens wont be as good, worry about floods more, more difficult lighting setup, limited & softer macro's
Pro's, Try & don't like - return or sell on Ebay, MUCH more affordable than other options, lets you get your other foundational gear now and upgrade the case later, doesn't lock you into a system (keep your foundational gear and upgrade the body and case as this platform matures), 2x - 4x lower loss if flood or stolen
Thoughts?
** Update - I was able to get the lens specs on the SONY website and it looks like this might work. I bought both camera housings for testing and pending the results I'll keep one and sell the other. Stay tuned!!