Perhaps, but I don't think that's likely - MS for one is definitely trying to get all the 360 owners to upgrade to XB1, rather than keep them on 360.
In 2013 that was certainly true - AAA exclusives for the X360 were basically dead...
In 2014, Titanfall (the first 'great hope' of the XB1) was also released on the X360. It shouldn't have been hard for the X360 version to mysteriously vanish...
I mean what good would that accomplish in the long term? It would just see MS cede the 8th gen to Sony and they can probably make more money off XB1 owners than 360 owners (margins on the XB1 hardware itself, additional controller sales, higher game prices, and less impact on new game sales by a huge used game market and large library of AAA titles that you have on 360).
Stalling next-gen to allow MS time to sort itself out? I don't know. And it's quite likely that MS didn't really intend to encourage consumers to stick with the X360.
It's just something to consider, there's no actual evidence that X360 owners are upgrading slower.
A final quirk is that "slow upgraders" could be seen as a group who don't see value in their "intended upgrade route". It's entirely possible that slow upgraders will be more likely to purchase the "other console".