Most likely the products had stopped selling, so Yamaha announced their discontinuation to push the last few people that were on the fence into making a purchase, then call it a day.
To their credit, Yamaha put Songman and Diva front and centre on their English social media, as well as producing video ads and tutorials. It's more advertising than any other Engloid has been given, and more than most music software releases. If he was previously unsuccessful, I hope the new attention on Songman will inspire more usage than he would have otherwise received, though I feel sorry for anyone that wanted to buy him and doesn't have the funds.
I have my fingers crossed that Yamaha has more plans for Engloids and V5, as it was nice to see some interaction between them and the English speaking community. I think there's still a lot of potential untapped.