You never know what will happen.
The 360 will always perform well in NA although there has been a small fight back with the Slim who knows how long this will happen for though, but reckon there will be similar sales of the 360 and PS3 in NA for the foreseeable future.
The PS3 is now starting to outsell the 360 in Others and this will continue for the forseeable future although it won't be huge numbers of a difference IMHO.
In Japan though, this is where the difference could in fact make a difference. The PS3 has sold nearly 1m units this year so far compared to under 300k for the 360 even though the 360 had a surge and the PS3 had terrible times.
For there to be a chance in the short term (ie over the next 2 years), then the PS3 must outsell the 360 by approx 2-3m units by the early part of next year.
Although I still see the PS3 having a longer life than the 360 over the course. Don't forget that the 360 has a solid 12 months head start in NA and 18 months of a start in Europe, so the the PS3 has kind of catched up, but the price has been the killer for Sony.
Prediction (June 12th 2017)
Permanent pricedrop for both PS4 Slim and PS4 Pro in October.
PS4 Slim $249 (October 2017)
PS4 Pro $349 (October 2017)