So unless the next iPP has some seriously killer hardware, I don't think I'll upgrade. Perhaps to the iPP3 I will.
I think what you are describing is, roughly speaking, also true of all iPad models. There were some exceptions in the early days like the jump to retina, but for the most part today I think that many people hang onto their iPads and skip at least a couple of models in between.
As an Apple shareholder, I'd really prefer that y'all always upgrade to the latest model every year, or even more often.