Theres truth to that.
Wouldnt be a surprise, if they outsold their own forecast by atleast a million imo.
I can't think of any instance where a console manufacturer has lowered their original forecast in an attempt to do much better than expected. What their downward revision to 13.5m (after the original 16m had already been revised down to 15m before) most likely means is that it's going to be all downhill for the PS4 after Black Friday. Last year's December in the USA was already weak, but in 2019 it's going to be even worse. Europe has less emphasis on Black Friday, but holiday sales overall will also be down from last year. In Japan it looks like Sony won't match last year's deal and perhaps won't offer a deal at all.
Afterwards, January to March 2020 will be uneventful for PS4 hardware sales except for Final Fantasy VII at the backend. The PS4 should be down significantly year over year for the final quarter of the fiscal year, hence Sony's forecast.