it's only going to be the 'base case'/'cooperative case' that will become indistinguishable, e.g. Lightning channel opening transactions and cooperatively closed channels, because Schnorr "additivity" (which is not a real word 
) makes such transactions appear the same as a regular [1 (or more) inputs -> 2 outputs] tx, because there is only 1 aggregated signature (because additive signatures, despite 2 parties signing the tx). Currently, spending outputs from that kind of transaction reveals it to be a 2 of 2 multisig that had alternate script paths, not so with the same tx script using Taproot/schnorr.
) makes such transactions appear the same as a regular [1 (or more) inputs -> 2 outputs] tx, because there is only 1 aggregated signature (because additive signatures, despite 2 parties signing the tx). Currently, spending outputs from that kind of transaction reveals it to be a 2 of 2 multisig that had alternate script paths, not so with the same tx script using Taproot/schnorr.This is perhaps ignoring the forest for the trees, those distinguishable lightning txn are relatively uncommon. 2 of 3 multisig and various multisig or timeout keys are about half of all transactions. Taproot should eventually allow most of those to look just like single key wallets. It'll also let users improve their security by using multisig without increasing their fees or making their transactions stand out at all.