I think it is unlikely that apple will anounce a major upgrade to any applications before Leopard is let out of the paddock. It would be barmy to 'cripple' an application with 10.4ness when it is launched when there is the joy of 10.5 in the wings. Just think resolution independent gui for sculpture so you can actualy see what your doing.
I would never expect apple to release a big Logic update before 10.5...but they could certainly *announce* an upgrade now and ship it some time soon after Leopard. It's not like they don't have internal versions of 10.5 that they can use for testing and demos.