I will bet 99% there will still be a Nexus phone released this Fall. Come October / November, Google will be selling an LG made Nexus-Five, running Android 5.0, with a 5" screen, on the 5th birthday of Android. That is almost guaranteed.
And Motorola will release their new "X" line of phones this Summer / Fall, but they won't be pure "nexus" style devices, will run a stripped down version of Motoblur, with a little bit of carrier bloatware. These "X" phones will not be 100% pure stock vanilla Android, most likely 75% stock, mixed a little bit with the new Motoblur.
So come this Fall, we will see both a Nexus-Five phone, and Motorola "X" phone.
I suppose in the future couple years away, we might finally see an Google only made "nexus" phone, all made in house from Motorola engineers and manufacturing, with no Motorola branding on it at all. But not sure if Google has plans to really turn Motorola into a in-house Google manufacturer ? Or will they just try to keep them always as "Motorola" branding ?