Well, this raises the question of what are the principles upon which the new hybrid is built? Is one component system going to be the foundation, and the hybrid is built upon that set of principles? Will it be all principles of all the component systems? Will it be a limited subset of principles drawn from each of the components, but not the complete universe of principles? And if principles are taken from the different component systems, how well do they integrate and function as a consistent whole?
The answers to these questions will affect what works within the hybrid and how coherent the system is as a whole.
I'll give a vastly oversimplified example. Wing chun is seen as a "short range" striking method (i don't exactly agree with that, but don't want to get into the particulars at the moment, so as I said, this is a vastly oversimplified example). Tibetan white crane is seen as a "long range" punching method (again vastly oversimplified, and again I don't really agree with that, but it works simply to illustrate my point).
So let's say we want to create a new hybrid that combines these two methods, with the hope that we can become more effective when punching at both shorter and longer ranges.
What is the foundation of this method? Let's suppose we are more fluent with wing chun, so we use that as the foundation. We are less fluent with Tibetan white crane, but we are familiar with the body of primary techniques, and we want to integrate those into our hybrid, built on top of the wing chun base.
The problem is, white crane techniques are designed to work on a particular foundation, unique to the Tibetan system lineages. Yes, they are punches, but they are trained in a specific way, unique to white crane. THEY WILL NOT WORK IF PRACTICED ON A WING CHUN FOUNDATION. That is simply the truth. Tibetan white crane is not just a collection of techniques that are to be swapped in an out on a whim. It is a physical education that teaches you how to engage the body as a whole, and the specific techniques manifest that concept.
This hybrid would be a Frankenstein's monster, built with good intentions, but simply not functional.
And as two distinct methods that are primarily punching in focus, I say that if you really understand either of these systems, then you will understand that they are NOT limited to short or long ranges, respectively, but that either system can be equally functional at either range. So it actually makes no sense to try to hybridized them together. You are better off just working to gain a complete and deep understanding of one or the other system, and that is all you actually need. No need to clutter up your training by trying to hybridize them.