It is not yet a done deal, but here's the report from the ISAF web site:

In 1999, ISAF formally approved the inclusion of a multihull discipline at the ISAF Youth Sailing World Championship from 2004 onwards.

In 2002, ISAF developed a criteria for builders to submit designs for the youth multihull, which led to a four-day trials in Quiberon, France in 2003, at which nine different designs from five builders were evaluated (including the Hobie 16 with added spinnaker).

The nine designs were eventually short listed to five, two, followed by a further process of assessment and evaluation which reduced the choice to two, including review of the production facilities, availability, distribution and price during 2004 by the Youth Multihull Evaluation working party chaired by Oliver Bovyn (FRA).

Olivier Bovyn (FRA) recommended the unanimous decision of the working party that the Sirena SL16 catamaran designed by Yves Loday be selected as the youth multihull for the ISAF Youth Sailing World Championship. The ISAF Executive Committee supported the proposal and will make the same recommendation to the ISAF Council at the 2005 ISAF November Conference.

The Executive Committee recommendation will detail the Championship at which the class will be first introduced to replace the Hobie 16 and whether there will be alternative equipment for the multihull event, as is the case for the other youth events. Prior to use at the Youth Worlds, the SL16 will need to achieve ISAF Status. The SL16 is a twin-trapeze, three-sail multihull retailing at approximately EUR 11,000.