They used to have Nvidia gpus as an option (mine is, from 2014). Soo.. looks like they are staying away from Nvidia now
My late 2013 was Nvidia.
I'm not sure "tick tock" is the right word. The MBP used AMD in 2006, NVidia from 2007 to 2010, AMD in 2011, NVidia from 2012 to 2014, and 2015 is AMD. It's actually a break in the pattern for them to use AMD chips two years in a row.
And the laptops tended to die because of that (mine is, from 2010)