Galileo HAS allows precision down to 30cm with enough integration time. Without additional external data.

For free.

Receivers slowly hitting the market now - a year ago this was only receivable by SDR-driven devices.

"with enough integration time" — the article is about live navigation, which generally can't afford that.

You can get integration time while driving. You combine accelerometer and gyroscope data to cancel out movement effects.

With SBAS 1-2m precision can be done easily in the US and EU. Most of the time enough for any navigational use.

Pretty much all GPS/Galileo receivers are able to receive and decode these overlays.

That's not so good. 24-channel GPS can do <1cm today while moving (that's RTK) using (free in most areas) WAAS. Fusion constellation many channel GNSS receivers with clear terrain can do about as good without DGPS (of which RTK is a subset). There's really no reason not to use as many constellations and as many satellites as possible to reduce error more quickly.

I really hope QPS works, becomes available to the public, and decreases in cost quickly because it would make GNSSes more of a backup and calibration system than a primary system. Hybrid location chipsets in mobile handsets use a fusion of many technologies and techniques which would be really cool to have QPS especially for underground metro systems and inside buildings with lots of signal-attenuating materials.