We will have more savory things, but not quite on the level of lasagna and what not. Right now we have the Spinach Egg Pie, and we can always add more things like that in the future. :) I would personally love to see some savory Borekas in the future!
No. Those ingredients would just get expensive just like the current things, so it wouldn’t really help the situation at all. Now that you can get the bag from the Millionaire Center, which includes vanilla extract, we’re not adding more to the donation center. The prices will lower once the hype dies down, especially since things like the extract are lower rarity so you can restock/vend it.
we've had edible books before (like one's in Pete's Quest Shop) so I wouldn't be surprised if one or two books came out this way :X