It's still about content and integration, as far as I am concerned. An arranger, even MORE than a workstation, stresses things to the absolute limit by needing total integration right from the start. Arranger players are basically 'I need everything, and I need it NOW!' just to get the basic operation that an OOTB closed arranger provides. Today I might be playing oldies, tomorrow funk, the day after, jazz.

You buy an off the shelf arranger, you are going to be able to do that, at least competently, the day you buy it. Until the software arrangers start to come with the quality of INTEGRATION of sounds that hardware ones do (I know that, individually, software sounds completely destroy a closed keyboard's sounds, but try to find an entire sound SET that is as well balanced and as comprehensive as a closed one, well, I'm still looking!) and a style selection as varied and as well suited to the samples they play as a hardware ones are, these things still don't address the needs of the majority (the VAST majority) of the market.

When one of these things comes out where you can buy one, turn it on, sit down and play style after style (of whatever genre you feel like) that utterly annihilates any closed arranger, then the world will change.

Until then...