If his supporters all vote more than once, and if it is not caught and corrected, then Trump will certainly “win” a second term. But is there any evidence that both of those “ifs” will be fulfilled? Is their any evidence that either will be fulfilled? Because so far it seems like scaremongering to me.
P.S. If no election were to take place, then Pelosi would not be re-elected to the speakership either. And since her current term would also expire in January, she would not be eligible to become president via the line of succession. Instead, the presidency would fall to the president pro tempore of the Senate, which is currently Chuck Grassley. Since he was re-elected in 2016, his term will not have expired by next January.
The only case in which Pelosi becomes the next president is if the election does take place, Pelosi is re-elected to the speakership, but the presidential race isn’t decided by 20 January 2021. In that case, both Trump and Pence’s terms will expire at a time when Pelosi is eligible to become president via the line of succession.