Harare - President Robert Mugabe on Monday fired his deputy Emmerson Mnangagwa, the man who for so long looked like he would succeed the longtime Zimbabwe president.Here's what you need to know:Unexpected?Not entirely. Mugabe - and particularly his wife Grace - have been stepping up their verbal attacks on Mnangagwa, 75, for weeks now. The first couple were outraged when Grace Mugabe was booed at a rally in Bulawayo on Saturday. That was blamed on Mnangagwa bussing in his supporters. Grace Mugabe led exactly the same charge against a vice president in 2014, when she got Joice Mujuru fired.How has Mnangagwa reacted?His spokesperson, Nharo Gwatidzo told Bloomberg on Monday evening: "There's nothing to say or do... we've been fired." That's in keeping with Mnangagwa's character as we know it. He has stoically refused to be baited by Grace.But why was he fired?Officially the line is that he "consistently and persistently exhibited traits of disloyalty, disrespect, deceitfulness and unreliability". Unofficially, analysts say it's because he - like Mujuru before him - represented too much of a challenge to the Mugabes as the president enters his mid-90s.Any chance of a coup?It's long been suspected that Mnangagwa has the backing of some top military officials. But as for the lower ranks of the army: no-one knows how deep, if at all, their support might run. Social media was awash with speculation yesterday that Mnangagwa might actually leave or be about to leave the country. For now, there's no evidence of that.What does this mean for Grace Mugabe?It means she's got her way and got Mnangagwa out of the direct line to power, at least for now. It means, at least on paper, that her G40 faction (ex-info minister Jonathan Moyo, Local Government Minister Saviour Kasukuwere etc) is in a strong position. It also likely means she will be made a vice president. That doesn't mean that there'll certainly only be her and Phelekezela Mphoko in the hot spots: there have been moves for THREE vice presidents.And for the opposition?No-one's asking that.. yet. The main opposition Movement for Democratic Change has its own problems: Morgan Tsvangirai is seriously ill, there are struggles within his party as to who should succeed him and the opposition isn't doing well on getting its supporters out to register to vote. Could Mnangagwa's dismissal mean a weakened Zaunu-PF? That's obviously not what Mugabe himself is banking upon. Time will tell.What Zimbabweans are saying on Twitter:Canterbury-based law lecturer Alex Magaisa: "The croc (Mnangagwa's nickname) has run out of water."Journalist Clarkson Mambo: "Is @ZANUPF_Official going to expel former VP Mnangagwa from the party or will he be demoted to an ordinary card carrying member?"Brezh Malaba, also a journalist: "I told you to expect a BIG announcement."@ddzmatara: "The myth that ED was too big to be fired has been busted. He is but an ordinary man after all."