the funny thing is that an arranger keyboard for live performing is a bit of a contradiction in itself. People going out, and certainly the younger ones, want to be entertained and could not care less whether it is live, pre-recorded, karaoke or whatever definition you want to attach to it. they DO want the "feast of recognition ". Whether it is Elvis or Beyonce that you are performing, they want to recognise the song and generally ( with the odd exeption ) they prefer the song to be as close to the original as possible. Hence the many SongStyles that in particular Yamaha is famous for.
But an ARRANGER keyboard as the name suggests lends itself uniquely to arranging a song even in a realm beyond your wildest dreams. Sometimes these new arrangements are so far removed from the original that people cannot be bothered. If they recognize the song at all they will probably remark that it is way of base. Personally I have had no problems with that as I rarely perform live, and never with my arranger keyboards.
By contrast I have often endeavoured to firmly uproot the original arrangement of a song, yes at times even beyond recognition. Hence I think that for the time being the arranger keyboard will be around for some time to come but that for live performances it will dwindle into obscurity within the next 10 years. ( though many choirs for instance often have an arranger keyboard, be it that they are often used for their sounds, so as a workstation really, rather than for their styles.
Just my thoughts,

regards,
John