Signatures are indeed much more compact for larger ring sizes BUT the computation time required to verify them is similar to the time that the current RingCT would need for large size . So it's not possible to scale to ring sizes such as 100k+. One needs to see what ring sizes are reasonable but I assume a reasonable ring size is certainly below 1000, and probably also below 100.
Still, the improvement in terms of transaction size is tremendous given that space in the blockchain is a very scarce resource and can help Monero scale to larger rings than currently used.