Well, certainly, augmenting the capability of an existing tactical transport with a cargo bay/ramp centreline system for refuelling helicopters and light attack jets would seem highly attractive.
But, without substantial redesign, the 146 simply has the wrong configuration. Short wingspan (86 ft as opposed to the KC-390's 111 ft) plus 4 engines effectively rules out a twin AAR pod layout. The 146 doesn't have a ramp either, so a complex, permanently mounted fuselage unit would be required which would reduce multi-role capability. The 146 carries not many people not very far and not very quickly - but its plus point is its very good short field performance. To modify the aircraft in order to provide rather limited refuelling capability just doesn't seem cost-effective.
If you want a good general purpose tactical transport with the potential to include a centreline hose capability, I'd suggest the C-27J with a modern generation centre hose drum unit. You'd probably have a max fuel capacity of around 12000 kg and, with a variable drag drogue, a speed range of 105-250KIAS at up to about FL150 which would suit most RW, V-22 and mutual C-27J AAR needs. But clearly not in the A400M class of capability.
Moving up the scale, the KC-390 has sufficient wingspan for 2 x AAR pods and the potential for a centreline unit as well, particularly if mutual AAR is needed. Total fuel capacity somewhat similar to a C-130 at a rough guess, so supporting light attack jet deployments would certainly be feasible.
Last edited by BEagle; 2nd Jun 2010 at 14:05.