For this to happen it would require no government being formed after the fourth elections, and also after 5th elections which would presumably take place at earliest in August or September.

While Gantz might still be holding out some sort of hope for this to happen (I don't know that he is, but it would definitely be interesting to see happen), Netanyahu is going to do everything possible, probably short of nothing, to make sure it does not happen. You can be sure he will try everything possible to form a government, even just a temporary one and one relying on the Arab parties, just to get a government sworn in to get that other situation behind him. Once that situation is no longer an issue, Netanyahu can continue through these elections while remaining Prime Minister of all the caretaker governments.

His latest move though is to try to get it over with by passing a law that says so..

MK Shlomo Karhi (Likud) has proposed a law that would put an end to the unity government (which is now a unity transitional government)  with Kachol Lavan. If the law should pass and the unity government canceled, Netanyahu would have the ability to fire all Kachol Lavan ministers, including Gantz himself and cancel the rotation agreement.

source: Behadrei

I am not sure what is required for a law to allow Netanyahu to fire the other members of his government, considering the government already collapsed and went to elections, but it seems there is a way for this to work. 

I also have no idea if the Likud has the numbers behind them to accomplish this, but I guess we wait and see. Maybe there are enough other people upset at Gantz to support it even if they do not support Netanyahu.

This is another example where you see that Netanyahu and his people have that killer instinct to win elections at all costs, and his opponents do not. The opponents have had the chance, and once again have the chance now, to pass laws and replace key Netanyahu people in Knesset, but they do not take advantage. They just do not have that killer instinct. Maybe they don't even want to win.