Games Workshop shows that the lifetime of a miniatures game is significantly longer than 5-10 years.
Don't even attempt to use Games Workshop's work in the miniatures game field to justify why WotC should have continued to produce their RPG. If you want to attempt an apples to apples comparison of WotC's licensed RPG to another company's RPG, that's all well and good. But GW's Warhammer Fantasy, 40K, and Lord of the Rings Miniature games are COMPLETELY different animals than the WotC Star Wars roleplaying game.
Games Workshop's miniatures games are the ONLY reason that company is in business. And their miniatures sell for a heck of a lot more than any of the WotC miniatures ever did. So trying to use GW as a reason why WotC should stay in business with the Star Wars license is folly at best.