There is a great and long-standing precedent for this: Richard Jackson's Garden... a show that is improved immeasurably by the absence of the named show host!
Many of the presenters who have been knocking around for a while do regularly do shows on their own, without even a guest. Some of the more recent batch do also... and in Sara Griffiths case it is the only time she is barely tolerable to watch. Julia, Jill Franks, Ali K, Charlie have all done shows on their own. I have to put in a word for the hilarious double-act which is rarely unleashed on an unsuspecting public: Dale and Charlie. They should have these two on air together more often. Dale and Charlie separately are also excellent when teamed up with one of their female colleagues. These double-act shows are usually jewellery shows and there are no guests at all, just the two presenters. I find them quite enjoyable. They are more fun, and as both Dale and Charlie (particularly Charlie) are very knowledgeable about stones and cuts etc, they are frequently quite informative.
Ali Young used to have her "In the Salon" shows without guests, but hosted by another presenter. That was also a format that I personally found enjoyable to watch.
Two presenters and a guest seem to me to be overkill unless they are doing proper Q&A segments to the show (as it means less obnoxious reading out of tweets etc by the main presenter). They've done this a bit with No!No! and also with Catherine Huntley's tech shows.