Here's the part of the CBA about cancelled games:
Cancelled Games. If one or more weeks of any NFL season are cancelled or AR for any League Year substantially decreases, in either case due to a terrorist or military action, natural disaster, or similar event, the parties shall engage in good faith negotiations to adjust the provisions of this Agreement with respect to the projection of AR and the Salary Cap for the following League Year so that AR for the following League Year is projected in a fair manner consistent with the changed revenue projection caused by such action.
I'm quite sure the NFL wouldn't be able to not pay players solely based on the article PFT talked about.
The two provisions are not mutually exclusive. The NFL might try to use the standard contract provision as an out if the start of the season is suspended, while the CBA provision would force a negotiation into reduced e cap in the subsequent year.
If you hung your hat solely on the CBA provision, and the entire season were to be cancelled leaving 2020 revenue near zero, the implication would be that there would be near zero $ in the player cap pool for 2021 which is of course impossible.
Of course taking the two provisions together there is still a massive hole: start the season on time, play one game or a few, and then have to cancel the rest. The 2021 cap reduction to offset lost 2020 revenue would be massive and still untenable. To illustrate, the dead cap on the Packer roster for 2021 as things stand now is $98 mil. There are only a couple of players whose 2021 dead cap is greater than their 2021 cap numbers, specifically Gary and Savage being the ones with dollar differences of note. If you lose half the 2020 season, and significantly more than half the revenue, while cutting the 2021 cap in half or more to make up the difference, the Packers probably wouldn't get to a roster of Gary, Savage and 51 minimum salary rookies after cutting everybody else. The entire league is in the same boat, give or take.
As things stand now, even if playing all the games for TV with sharply reduced attendance to enforce some kind of social distancing, the revenue shortfall would be massive still. Only about 50% of NFL revenue last season came from TV with the lions share of the rest from the stadiums: tickets, skyboxes, concessions, parking, merchandise, associated interests like the Titletown district and Hall of Fame which are fairly common these days among franchises. Those asscociated interests are probably being slammed already with reluctance to travel among the general public.
If one were to assume a default to a full season of TV games, 20% butts in seats, no preseason revenue, and sharply diminished stadium and ancillary property revenue, that's still an untenable amount of lost revenue to be carved out of 2021 cap while also paying all contracted 2020 money. The NFL and NFLPA would have to throw that provision out the window and spread the cap loss over multiple years.