Dysonman1 and others here have proved an excellent point
The Kirby is now different-enough in its own way to carve out it's own new niche. I suppose if Hoover was still selling Concept Ones as their only machine, they would prove similarly niche, but also stand their own ground in terms of performance and reliability. Kirby is also still fully-grounded in door-to-door sales, which maintain their own sales tactics and merits, outside of most company strategies, which has tremendously helped Kirby's continued success.
Even still, I'm very ready for something bold from Kirby. They have almost 3 decades now of regular complaints from everyday customers to address (weight, bulkiness, the extra steps to use tools, etc.). A much lighter-weight machine could still (easily!) achieve the same performance as their current models. They could address all common complaints of Kirbys today, and improve upon their existing product, without dropping the reliability at all.
Although excellent carpet cleaners and rugged, during my vac shop days, whenever a customer was buying bags, I asked how they liked their Kirby. The response was always negative. Owning a Sentria II (which I got for $10 at a flea market), It's sad to see something that works so well was so quickly abandoned by their buyers, despite the steep price.