Current ACH system (which is mainly Federal Reserve), probably yes.
Banks, probably not.
But remember that there is more than just the USD.
Take the UK's hierarchical system:
We have CHAPS as the GBP RTGS, equivalent to Fedwire for the USD.
But we also have systems such as BACS, Faster Payments and other deferred net settlement systems (which I guess also includes Visa/MC settlement, etc) that do internal netting and then settle gross over CHAPS. People use them because they're cheaper and offer other advantages (e.g. related to liquidity requirements or membership rules)
That is: in my mental model, I see BTC+Bitcoin Network as an analogue of USD+Fedwire or GBP+CHAPS.
The key question, thus, is: do we see the Bitcoin network scaling to the point that the deferred net settlement systems (e.g. BACS) are not required? Or do we expect this federated/hierarchical approach to emerge in the Bitcoin world too?
My prediction is that, just as BACS and Faster Payments in the UK would continue to exist, even if everybody was allowed to use CHAPS, I predict that net settlement systems for BTC will crop up, which internalise transactions where possible and settle gross amounts over the Bitcoin network as required.... even if Bitcoin network scalability is a non-issue or transaction charges don't become prohibitive for small transactions.
But I guess time will tell.
(and sorry... I feel like I'm banging on about this on a thread that isn't really about payment systems, which wasn't my intention....)