Guise,
You are missing the point and ignoring the obvious. If there were absolutely no market for 76 keys for arrangers, Korg, Ketron and Roland would not be CONTINUING to make 76 key arrangers.

You know why they do? Because they realize that it does know harm and if done right would have minimal effect on R and D and production.

They know that persons who would buy a 61 key would also buy a 76 and the persons who would buy a 76 key would buy the 76 key arranger.
A profitable business strategy that Yamaha and its believers don’t seem to understand.

As this discussion is continuing to reveal, whether Yamaha makes a 76 key arranger has nothing to do with markets (from Yamaha current market prospective). In fact, the companies who would have something to worry about are Korg, Ketron Roland Lionstrack and others.