Fears of the collapse of Sharon's centrist Kadima Party may turn out to be overblown. Obviously, the situation is very fluid right now and it would be difficult to tell how people will react over coming days and weeks. But for now, people look like they're staying put:
Poll: Kadima would get 42 seats if led by Shimon Peres
By Haaretz Service
Public support for Prime Minister Ariel Sharon's Kadima party has not weakened in the face of the prime minister's deteriorating health and the expected end to his political career, according to a Haaretz-Channel 10 poll conducted Thursday by the Dialog Institute.
If the party were headed by Shimon Peres, it would still lead the race for Knesset, according to the poll. The party would be expected to garner 42 Knesset seats - a number similar to Kadima's standing in the polls before Sharon fell ill.
The poll also revealed that Interim Prime Minister Ehud Olmert, currently the most likely candidate for Kadima leadership, would secure 40 Knesset seats for the party if elected chairman.
If Justice Minister Tzipi Livni took over Kadima leadership, Kadima would be expected to win 38 seats. Headed by Transportation Minister Meir Sheetrit, the party could expect to win 28 mandates, and only 26 seats if Defense Minister Shaul Mofaz were chosen to head the party.
http://www.haaretz.com/hasen/spages/666920.html***
Olmert will probably lead the party, as he is already Acting PM and as Sharon's right-hand man will likely be retained by Kadima, despite having been relatively unpopular among the Israeli public according to a lot of the reports I've read. Peres benefits from his status as Israel's elder statesman, but he's always polled well and has failed to ever win an election despite having led the Labor Party time and time again. Plus, he's even older than Sharon and many probably won't want to take that risk. Tzipi Livni is, according to Wikipedia, quite young (47), very close to Sharon, a former Likud Centrist, and the most popular politician in Israel but without any leadership experience it's unlikely she'd be selected as the top candidate.
Nevertheless, this should hopefully dispell some fears that the return of Netanyahu is imminent.
* NOTE: The chart above seems to contradict the text of the article, which says Mofaz should garner the party 26 seets. The graph shows him garnering 36.
There's some good analysis in this piece from Haaretz:
http://www.haaretz.com/hasen/pages/rosnerBlog.jhtml?itemNo=666703&contrassID=25&subContrassID=0&sbSubContrassID=1&listSrc=Y&art=1