Like.

BUT. Could be easier. Don't need a Master Block.

1) Throw away EVERYTHING except the Block-header for blocks older than 1 day / (..or the longest re-org imaginable ). The block header is the ONLY bit you really need - as it has the POW. Also it links back to the previous block header, so we have our 'Proof Chain' back to the Genesis block. (Which would be tiny). But still packed with ridiculous levels of POW-er..

2) You need to store the deterministic UTXO root hash somewhere in the block header. Changes for every block obviously. But everyone would agree on  it.

3) That's it.

As with your design we lose the TXN history - but we keep the POW chain that led us to the present day UTXO.

So.. doing the Maths.. it would be about :

576GB (as you calculated for 1 billion txn a day)+ UTXO database size (orders of magnitude smaller than 0.576TB) + the proof chain size (tiny).. forever.

Whether there would be any point to keeping the TXN history - is debatable..