Could it be possible that if another ice age were to come, perhaps in a few tens of thousands of years or so, that it would dry up the amazon rainforests?

And in it's place, praries and grasslands would spread throughout the basin.

What animals in, and/or around, the amazon would be best adapted to live in the dryer more open conditions of the amazon grasslands thousands or a few million years from now?

Got the idea from the Future is Wild, but would like a more accurate and more modern theory.

same answer as your previous question. almost anything is theoretically possible over that massively long time scale, as Dr Hone has repeatedly told you.