I would not be surprised if Mazda discontinues the CX-5 turbo, at least in the US. Or maybe keep the turbo but eliminate the Signature trim once an AWD version of CX-50 is available.
As with the CX-3 / CX-30, it does not appear there will be much difference in interior space or appearance in the CX-5 vs. CX-50. It made perfect sense that the CX-3 was discontinued in the US. The Canadian upper trim CX-3 with 148 HP bleeds into the lower trim CX-30 with 155 HP. Why both are still sold in Canada is something peculiar to that market which I do not understand.
Further, CX-30 is not touted as a "premium" vehicle as CX-50 evidently will be with the 6 cyl / 8 speed, initially in RWD only, suggesting something along the lines of a 260 HP vehicle in base configuration. A CX-5 Signature at $39,000 will bleed into the CX-50 trims once AWD is available, probably starting in at low $40,000's.
We'll see, but what Mazda is doing is peculiar--two models that are sized about the same, look about the same, where performance and features have trim overlap. From a marketing standpoint that's a bit of buyer cognitive dissonance.