With the imminent replacement of the four-cylinder Daytona 650 with a slightly larger displacement three-cylinder machine, Triumph is retreating from direct competition with Japanese manufacturers. From now on, apparently, Triumph does triples and twins, just like the old days.
It was undoubtedly a painful lesson for Triumph, which never developed a fully competitive 600cc sportbike, and ultimately resorted to a big bore 650cc machine to match the Japanese in horsepower. You may recall that Triumph was also developing a larger displacement four-cylinder superbike, but dropped those plans after the Daytona 600 had so many teething problems.
Triumph has proven that it can build fine motorcycles, but with its heritage it makes sense to stick with twins and triples (at least, for now) where it has less competition and a marketing advantage.