Companies like Chainalysis and TRM have contracts with almost every federal law enforcement agency. They make this kind of analysis almost trivial.
I wonder how many wallets you would need before it becomes a problem to track. I would guess in the millions or more since graph algorithms are pretty efficient these days.
And there is the issue that what is inefficient today may become efficient tomorrow. The blockchain will be there waiting for new forensic techniques.
How long of a linked list do you need to be unable to reach its tail?
There are exchanges which allow transactions from e.g bitcoin to monero. As soon as you’re on such a private chain, you most likely broke the link.
I was thinking more along the lines of a directed graph where each of the wallets pass the funding received to multiple other wallets before the money finally converges to a destination wallet, it doesn't have to be a straight linked-list style line of wallets.
In any case, the transaction costs alone probably makes this prohibitive for more than a few dozen wallets.