I think that the trend is toward a fusion between synths and arrangers; of course an arranger with all the editing possibilities of a synth would be way too complicated and expensive, but if an arranger like the Roland VA7 offers the same sounds as the XV series and some basic editing too, then the need for the editing possibilites offered by a synth is really questionable, unless you are mainly a studio musician.
The same thing goes for the Yamaha PSR 9000 and the new Motif: in this case it was the Motif to borrow some of the 9000's sounds!

Regards,
Andrea