Does it mean:
If the speaker Bertrand Audoin said on the day May 1,2011 "this might take as long as 25 years," he refers to that on May 1, 2036 we'll have found a cure for HIV?
(Of course it is not necessary to get the cure in the particular May 1, 2036, it just means the need of the time (the 25 years).
Context:
1 June 2011 Last updated at 00:05 GMT
New push aims to find cure for Aids virus
By Jane Dreaper Health correspondent, BBC News
More investment is needed to find a cure for HIV, the new head of the International Aids Society has said.
Bertrand Audoin admits this might take as long as 25 years, but he says a cure is the only way to keep ahead of the HIV epidemic in the long term during tough financial times.
More:
http://www.bbc.co.uk/news/health-13605224