Not sure I'd call it just a pipe, but maybe a series of tubes.

Well quite. So why are we living in this surveillance hellscape?

this is not correct. neither brave nor edge has committed to that.

as of yet, there's no (publicly stated) contingency plan if the upstream mv2 code is excised, but I could be mistaken.

This seems to be the only way forward from what I can figure. Helium's main selling point is that it's essentially degoogled chromium + a few miscellaneous patches & full uBlock. But once Google completely strips all that out of Chromium project, that won't be a tenable option.

I'm not sure what Opera/Vivaldi/et al. use for their native adblocking, but Brave's rust adblocker makes the most sense to me. Really it's uBlock's filtering lists that keep the whole thing working anyway.