Whenever I mention that I am hoping that Trump fires Jeff Sessions, people tell me that, as bad as Sessions is, whoever replaces him will be worse. I don't know if that is true. Sessions' successor would have to be confirmed by the Senate. Sessions got 52 votes in favor of his confirmation. Part of the reason he got that high of a vote is because he was a sitting Senator at that time and benefited from the good will of the other members of his caucus.. Sessions himself has been replaced by a Democrat and Joe Manchin, the one Democrat who voted to confirm Sessions, specifically cited the fact that he knew Jeff Sessions as the reason he voted for confirmation.
Whoever Trump would appoint to replace Sessions is not going to be a Senator. If nothing else, losing Sessions seat to a Democrat has taught the President, err, the President's advisers, I mean, the people on Fox and Friends not to do that again. But that takes away the one big thing that Sessions had going for him.
Of course Sessions himself had his own liabilities. He had a reputation for racism, including that letter from Coretta Scott King that prevented his appointment as federal judge. Trump's next pick might not have that baggage. But that in itself means that the next AG appointee would not be as bad as Sessions.
There might actually be a handful of people in the country who would be a worse AG than Jeff Sessions (Robert Spencer, for example), but I don't think they would automatically be confirmed, especially when the GOP us heading into a mid-term election facing a Democratic wave with their Senate majority on the line because of the President's widespread unpopularity.