There are no plans to drop btcd.  I'm interesting to hear in what ways btcd is not on par with Bitcoin Core.  btcd has a more modular code base, more readable code, better documentation, better test coverage, and supports everything that Bitcoin Core does along with a few things it either doesn't yet have or only has on branches and isn't part of master (for example, BIP0023 block proposal support).

Note, that we're talking about the full node daemon, not bitcoin-qt which includes the wallet stuff.  btcd intentionally does not have the wallet integrated which is something that Bitcoin Core still hasn't separated out even though I believe it is on their list of things to do.

EDIT: Oh I just realized you were referring specifically to the mining support offered by btcd.  There are no plans to drop support for that either and, as mentioned above, it even has support for BIP0023 block proposals which is not yet part of the Bitcoin Core mainline.