I think it would be very nice to have smaller RBs4011s in the future which can be dual-mounted in 1U. This would be very beneficial in situations where space is limited but redundancy is required. Currently the RB4011iGS+RM has width of 228mm. Shrinking it to ~216mm width per unit would be awesome. 1U has a width of 44.45mm, which means there would be 12.5mm left for the mounting tray. Thanks
The RB4011 is a nice platform. The fact that they made a WiFi version tells me that this iteration might be locked-in. However, they could release other variants to accommodate you. You might benefit from simply modding it yourself (take the board out and put it in a custom case).
No. I think a twin-tray version would sell very well.
+1 For this. Rack space is quite pricey.
board looks way smaller than the case:
From the picture it seems like 215mm, which means you can easily put two boards into one case, next to each other and it will nicely fit!
If you believe there is such market potential (which I politely disagree with) you can order big bulk of double-cases from china, order few RB4011s and sell the modded version. If you are right and if there really is such demand, you will get easy money with that. Or if you don’t want to risk that much, you can just design the case, place the order and sell just the case (and let customers to do the modification themselves).
But we all know thats not gonna happen, right? 
You never know, I’ve seen third-party rack mounts for double RB450s, RB493s and RB2011s, so it could happen for RB4011 too.
It’s easy for RBs with smaller boxes .. it only takes a rack-mounted “shelf” with 1-U front cover and appropriate holes cut out. With RB4011 that’s not so easy because of excessive width, one would need to move board to a (slightly) smaller case … I guess that outer box width could be down to 220 mm (if the board is 215 mm wide), 5 mm could just be enough for case walls and some board mounting clearance.
I don’t think that a case for twin RB4011’s is such an attractive option … it should be a narrower case for single RB4011 and a shelf to place two such units in parallel.
Used to use the 3rd Party rack mounts for the RB2011’s and they saved us mega bucks back in the day due to rack space being super pricey.
Would be mega if something like this was developed for CCR’s or CRS switches.