I doubt it very much. Fireworks is a strong package for web graphics. Illustrator is not designed for the same, and for that purpose, it's bloated and slow.
Even Photoshop isn't up to scratch with Fireworks' web stuff.... which is why, I'd say, it's still alive.
There's no point in panicking and changing to another package. I'd say it'll stay - but if it does get depreciated, it'll be rolled in to PS, not Illustrator. What's more, all the functionality would be maintained in a replacement product.