I have no idea if these rumors are credible:
The head of the World Trade Organization, WTO, confirmed Wednesday that the group was looking for bigger headquarters but refused to comment on rumours that this could be outside Geneva or even Switzerland…
‘Above all we need to be under the same roof,’ added Lamy who refused to be drawn on claims that the WTO had been approached by Hong Kong and Singapore with a view to moving the operation there. He said he would not fall into a trap of negotiating in public.
Trade Diversion 
Yes, it’s true. We know since library is in the basement of the WTO building and we’re being kick out so they can have more space. We also are looking for a new building so we had to find out about the WTO’s plans. They are looking for a larger building. Not clear where in Geneva, but the Swiss won’t let it go. Remember, when the GATT become the WTO, they had an international search for a HQ building. Bonn and other cities made a strong bid, but in the end the GATT staff did not want to move. My guess is the same thing will happen; outside bids used to pressure the Swiss govt.