From Nutanix's viewpoint, they will not want to make & support their own hardware, hence why the renewed deal with Dell makes sense, and why they are prepared to self-support on CISCO.
But CISCO want a walled garden that they alone control, which goes in the face of Software-Defined in the truest sense.
It is my suspicion that Nutanix has the means to properly commoditise the server platform into an SDDC, and so is a real threat to CISCO's UCS margins & customer control.
The question will then remain: how much control can CISCO maintain inside their (possibly shrinking) garden, or how much control will customer start to reclaim by such commoditisation.
Interesting times ...