@ZuWo: Reposting this gay marriage related post here. How do you see the situation. Does it have a chance? And am I right about how the constitutional change mechanism works?
Actually I'd wager that Switzerland would pass gay marriage via referendum by a surprisingly healthy margin. Yes I know it's Switzerland, but I think opinions in Western Europe have changed so dramatically I imagine even in the most conservative of countries it would grab a majority.
There were two polls conducted in February. One showing 62% of women and 46% of men in favour (with a straight Yes/No question) and one with 71% favourable or somewhat favourable towards gay marriage.
It seems the gay community thinks a referendum is too costly and demanding. They prefer parliament to agree on a constitutional amendment to grant legal protection for all couples, independent of their sexual identity. The Green Liberals have gotten it through committee in the National Council and will submit the proposal to the Council of States in November. So the process is already under way. I guess it could happen in 2016. You need a majority in both houses incl. a majority of cantons in the Council of States.
There are 46 councillors. 40 from 20 full cantons and 6 from 6 half cantons (Obwalden, Nidwalden, Basel-Stadt, Basel-Landschaft, Appenzell Ausserrhoden and Appenzell Innerrhoden), so 24 councillors representing 14 cantons will be required. So the small Conservative cantons will be the problen.
(though I might be wrong about the details)