If two states - should the land be equally divided for long-term stability?

The two-state solution as currently advocated, will give 80% of the land between the Jordan and the Mediterranean to Israelis -  but here are the demographics presented in this paper

Palestinians on the Verge of a Majority: Population and Politics in Palestine-Israel
Monday, May 12, 2008
Palestine Center Information Brief No. 162 (12 May 2008)
By Ali Abunimah
Palestine Center Fellow
On the eve of the 1947-48 war, the population of British Mandate Palestine (Israel, the West Bank and Gaza Strip today) stood at two million people. Jews, most recently arrived from Europe, were one third of the population and Palestinians'Muslims and Christians'were two-thirds.
Successive wars, expulsions continued Jewish immigration, and Israel's refusal to allow Palestinian refugees to return had a dramatic impact on the demographic character of the country. The combined result was the transformation of Palestine from a majority non-Jewish country into one with a Jewish majority.
This engineered Jewish majority has been used to bolster Israel's political claim that it has a 'right to exist as a Jewish state.' Today, however, the demographic situation is on the cusp of an historic tipping point where Palestinians once again constitute the majority population. This briefing will look at the current population, future trends and consider some political implications from Israeli and Palestinian perspectives.

The Population Today
As of December 2007, the total population of Palestine-Israel stood at just over 10.8 million people. Of these, 5.15 million were Israeli Jews; 5 million were Palestinians; and 657,000 were neither. Israeli Jews constituted under 48 percent of the population; Palestinians were just over 46 percent; and others formed the remaining 6 percent, as the table below indicates. Thus, today, 52 percent of the population ruled by the government of the Jewish state is not Jewish.

Totals at end of 2007 -  Israelis 5.154,300 or 47.66%
Palestinians (including Arabs in Israel) 5,003,446 or 46.22%
Others 657,100 or 6.08%

Yossi Sarid, a former Knesset member, recently compared Israeli policies to those of apartheid South Africa but maintained that: One essential difference remains between South Africa and Israel: There a small minority dominated a large majority, and here we have almost a tie. 
Israeli Prime Minister Ehud Olmert expressed last November that:
If the day comes when the two-state solution collapses, and we face a South African-style struggle for equal voting rights (also for the Palestinians in the territories), then, as soon as that happens, the State of Israel is finished .... The Jewish organizations, which were our power base in America, will be the first to come out against us because they will say they cannot support a state that does not support democracy and equal voting rights for all its residents.

from -  http://www.thejerusalemfund.org/ht/display/ContentDetails/i/2244

Sources: Israel Central Bureau of Statistics, Palestinian Central Bureau of Statistics, Peace Now (Israel).
-- but to continue to quote it...
Demographic Trends
The Palestinian population's annual growth rate exceeds 3 percent in the West Bank and approaches 4 percent in the Gaza Strip. While the growth rate of Palestinians in Israel is 2.6 percent, it outstrips the Israeli Jewish growth rate of 1.5 percent, according to official statistics.
The Palestinian Central Bureau of Statistics (PCBS) estimates that by 2015, the Palestinian population in the West Bank and Gaza Strip will exceed 5.5 million and by 2025 it will exceed seven million.9 Israel's Central Bureau of Statistics (ICBS) projects that by 2025 the Palestinian population within Israel will grow from over 1.4 million today (Israel counts Palestinians in Jerusalem in this number) to between 2.1 and 2.5 million by 2025.10 Meanwhile, ICBS projects that by 2025, the total Jewish population will be within a range of 6.3 to 6.8 million or about two million fewer than the combined Palestinian population.
Noted Israeli demographer, Haifa University's Arnon Soffer, predicted in the 1980s'accurately it now appears'that Palestinians would outnumber Israeli Jews by 2010. By 2020, he projects Palestinians will grow to 8.8 million while the Jewish population will number 6.3 million.
Demography in Current Israeli Political Thinking
Preoccupation about a 'demographic threat' from a looming Palestinian majority has long been a staple of Israeli politics, although it has recently taken on a new urgency. For many Israelis, 'Invading armies from neighboring countries seem a remote danger compared to the rapidly growing Arab population in Israel's midst,' wrote Haaretz's diplomatic editor in 2005.
 continues on http://www.thejerusalemfund.org/ht/display/ContentDetails/i/2244 - recommended.