Scenario for 2022
Far-right: Bolsonaro, of course. We still don't know if he will join Progressistas, Republicanos or PSL. I also include Amoedo in the group of far-right, but Novo did not well in the municipal elections in 2020.
Center-right: Possible names are João Doria (governor of São Paulo), Eduardo Leite (governor of Rio Grande do Sul), ACM Neto (mayor of Salvador), Rodrigo Maia (president of the House), Sérgio Moro (former judge and Bolsonaro's Minister of Justice) and Luciano Huck (TV star). The governor of São Paulo is always a natural candidate, since São Paulo has the biggest GDP and 22% of the country's population. But Doria has not high approval rate. Luciano Huck had friendship in the past with not so good people (Aécio Neves, Sergio Cabral, Sergio Moro, Eike Batista, Joesley Batista, Ricardo Electro and Robinho). He might become vulnerable in a campaign. Moro used to have support from the far-right, but this group considers him a betrayor.
PDT/PSB/Rede: I believe there will be a Ciro Gomes / Marina Silva ticket, although I don't believe they will be sucessful (Red Velvet and I explained why).
PT/PCdoB: Fernando Haddad (former mayor of São Paulo), Jacques Wagner (senator) or Flávio Dino (governor of Maranhão). Even if Lula have all his rights back, I don't belive he will try again, since he is very old and he knows that half of the population doesn't like him.
PSOL: No other name than Guilherme Boulos was mentioned until now. We don't know if Boulos will run again or if PSOL will make an alliance with PT in the 1st round
To what degree has the Brazilian mainstream center-right acclimated itself to Bolsonaro? If Bolsonaro is the most popular right-wing politician in the country (and assuming roughly 50/50 approval ratings, it means he has support from most rightists), would they even run a separate candidate?