GT5 was a mega hit of extreme proportions with 15m+ sales. No one is suggesting GT Sport will do those number - I am saying it will exceed GT6's lifetime sales - for all the reasons listed above. I'm pretty certain it will be well over halfway to that 6m figure by the end of the year.
Getting on for 6 weeks after release, Black Friday week, then Christmas, it's all about moving units. Right now GT Sport, along with Horizon Zero Dawn and Uncharted Lost Legacy, is Sony's key title to add value to bundles. Bundles that will generate 50% of the entire years PS4 sales in Nov/Dec. Individual units will be discounted and as a result GT Sport is currently the 6th best seller on Amazon UK as the Black Friday sales start. Bundling won't stop in the New Year, the above will all be key titles for retailers to add value to the latest Spider-Man or God of War bundle.
GT Sport had mixed reviews, but large sites like Gamespot, Easy Allies, Eurogamer all gave solid 8/10 marks. At worst it was getting 7/10's with the biggest complaint being content. After yesterday's DLC update you can already read about people picking it up who've so far been on the fence.