Hitler will not accept peace in the long run. If this means ruining Germany economically, he will do so and probably nobody will stop him.
If this means waging a war which is unwinable from the 1st campaign on (=> 1938), he will do so and a) either lose the war or b) he might be deposed by a military coup.
As a) would probably lead to conditions ending dictatorship, b) is the only option working in this scenarion.
A military takeover will in the mid-run lead to an authoritarian regime, though not with a general as figurehead (I do not see anybody like e.g. Franco in Germany). They will probably hide behind
a) Göring as Reichspräsident, thereby including a good deal of the NSDAP; if that is not desired or Göring not available
b) a weak but respected conservative political figure as Reichspräsident, perhaps von Neurath
c) my bet would be on a monarchical restauration within a few years, if Germany is lucky, Louis Ferdinand as emperor.
Parliamentarism will be limitedly revived in the long run, probably rather along the lines of the 1871 constitution, without the right to select the head of government, voting system back to first past the post, unlike in 1919-33. Also the KPD will certainly remain forbidden.
But, perhaps, they will also toy with different ideas, where political participation is rather based on your place in society (Ständestaat).
In such a scenario, the fate of the NSDAP IMHO depends largely on if and how they manage to get their act together as a political entity without Hitler. They might just implode, fractions fighting each other about "what the pure doctrine is", they might also remain the leading right-wing party if their organisation is intact. They do not lack personalities to lead, IMHO. If they do so, I see a long-term potential around 20% of the electorate (+/- 10% over the years).