The new wave of DSA-aligned progressives are running on an FDR inspired "Green New Deal." If they get enough victories in next year's primaries there could be a realignment of the DNC towards FDR style policies, so there very well could be an FDR type running in the 2028 presidential election with the support of the Democratic party. The wealthy donors who control the DNC would be forced to appease the base
It's likely to be a very chaotic affair given Trump's unwillingness to abdicate power. Unfortunately the only way I see trump leaving office peacefully is if his own party turns on him and votes along with Democrats to impeach him before the next election. Failing that we'll get Jan 6 two: electric boogaloo and we get to find out if they worked out the kinks.