While the result of the battle would likely lead to a loss of a good chunk of the Prussian army, I doubt such a peace would feasible unless the Austrians follow up that success with an invasion of Prussia itself. And even then, Prussia is sure to have another army ready to see the Austrians and their allies off.
They did, but it made heavy weather even of defeating the lesser states. Iirc it didn't even manage to beat the Bavarians until a week or two
after Koniggratz. So I can't really picture it "seeing off the Austrians".
The Bohemian campaign was "all or nothing" for Prussia - in some ways a bit like the offensive of 1918. If successful it would bring a total victory, but if not it would expose Prussia to total defeat. There isn't really any middle way. This is no doubt what Moltke meant when he told Wilhelm (who was wavering and considering retreat) that at Koniggratz they were fighting for "the very existence of Prussia".
At most, the peace would probably see the same indemnities, but probably either the loss of Silesia or Rhineland, not both.
Not sure I follow. Prussia won't concede either unless totally defeated - in which case it may perfectly well lose both.
The only power in a position to intervene is France, and Nappy III is still preoccupied with Venetia, and will be delighted for FJ to accept Silesia in lieu of it. As for the Rhineland, he'll be happy enough to see Prussia replaced there by a couple of minor states - even if they are ruled by Austrian Archdukes.