Just a quick few words on the subject...
The OP asked about the FUTURE of arrangers, not where they are now. We seem to have taken a sidestep into the current 'DJ vs. OMB' controversy du jour. I guess the only thing I'll say about that is... doesn't ANYONE remember how ridiculous old men singing Elvis tunes was, back when Elvis was first starting? Or some middle aged organist, pumping out tired covers of 'I wanna Hold Your Hand' back in the mid 60's?
Well, consider us doing a Black Eyed Peas cover now, or cranking up our arrangers to do 'I'm Sexy And I Know It'! How ridiculous we must look to the younger generation! As ridiculous as that 60's organist covering the Beatles...
Leave DJ'ing to DJ's. And leave covering trendy synth tunes to trendy kids with synths.
As to the FUTURE of arrangers, I'm with spalding here. Unless arrangers start adding loop and arp capabilities (and they are quite different from what we can currently do on arrangers), as we get older and arrangers remain incapable of producing anything remotely contemporary without sounding like the equivalent of that poor Bontempi player trying to cover the Beatles, what future CAN it have? It will gradually go the way of the 'home organ', relegated to dusty homes of elderly relatives the kids dread visiting (us, that is!) in case Granny trots out that bossa version of 'Hey Ya'!
Sadly, we have had a few attempts at a convergence of the VSTi/WS/Loop player and arranger, but all have fallen flat on their faces, either half-assed arranger sides, or half-assed WS sides, and all priced beyond their capabilities. The MS was SUCH a good idea... sadly left to the hands of a man unwilling to make it work. I have a nasty feeling we won't see it's like again. Dom has apparently seen the light, and abandoned any serious arranger development, choosing to concentrate on it's VSTi/WS side.
The majors seem to be trying to bend over backwards to avoid any mention of the word 'arranger', even as their WS's slowly approach them in capability. But, as we all know, an arranger is the whole package. Miss off several of the key things (inversions, linked fills, Songbook features etc..) and they fail pretty completely as a substitute. To be honest, I am not sure if we will EVER see the complete melding of arranger and WS, and possibly because of the bad taste most arranger players are leaving in the mouths of those young enough to tell the difference between what they listen to, and what an arranger sounds and works like.
So.... gradually, slowly, what could have been a VERY capable performance tool will get relegated to the status of the 'home organ'; irrelevant, dated, good only for oldies, singalongs, and entertaining the elderly.
What a waste!