I know Teremus has stated that any cards reprinted in the Foundation set will be usable....But what about those that aren't reprinted? Do they just disappear from my collection or just become banned?
Q: Will I lose my old art cards once the Foundation set is released?
A: "Any card that is re-printed in a Foundation Set that you have an original copy of is something you can use. Consider it a legacy version of the card, but so long as it’s in legal circulation, you can use whatever version of it you own." (Quote from Teremus - 'Infinity Development: March Edition' thread)
It's a lot simpler than most make it out to be.
If it's not available for purchase in the store, then it's not legal for ranked play. Other than that, absolutely nothing happens.
The first rotation does not happen for a long time yet, and won't happen until the first set of the next chapter is released.