I asked this question in the Wisdom of the Crowd:

Should Dr. Tan CB contest the next general election?

Here are the responses: (53 Votes)
68 % - He should contest as a leader of a coalition of non PAP parties.
26 % - He should get ex PAP MPs to join him to contest the general election.
4 % - He will not get much votes.
2 % - He should retire and look after his grandchildren.

See the pie chart at: 
http://www.wisdomofthecrowd.sg/chart.aspx?ID=1099