Of course I would be much happier if it was only $600 or even $350, too!
And of course an option to buy only a few blocks for those who don't want the whole package would be great. I, for my part, would go for the whole of it, and if all the blocks are available separately, then they might sum up to more than what I would hope to spend, given the price of the FAS Reverb plugin, $200 for a single block, although with improved functionality and sound. Maybe a discount model might be a good way - the more blocks you buy, the more discount you get.
Well, it's all only speculation right now, the only thing that is safe to assume from Cliff's comment to the OP is that an amp plugin will come out, and I think we can safely assume iLok2 protection since that is used for the reverb. I for one will immediately sell my Axe Fx II and buy the plugin, I am a studio/recording guy and play no live gigs at all, a plugin with Fractal models is ten times more convenient for me.