There are a few "howevers."
The suggestion that Manchin will be names is still a big "IF."
Also, we don't know how many Republicans voted "Yes," on the last bill because the knew John McCain would vote "No," and the bill wouldn't pass, so they were safe to vote "Yes."
But also, I don't fully follow the logic why Manchin would take the job. He's up for re-election, and it's a tough race. So, that could be a reason. BUT -- he's a smart guy. Taking a job in the Trump administration not only ruins his reputation, but it's likely a dead-end job, for an administration under powerful assault from investigation and which could collapse. And he also would know that his leaving would be a crushing blow to health care.
It seems very unlikely. But I don't know. Trump is apparently returning to Washington on Monday in a change of plans, for a "big meeting." That could be a press conference, and it could be to deal with cabinet position shifts. But that doesn't mean it will play out this way. Well...well see.