It sure looks like one. But your photo doesn't show the dustcap... If it was a cartridge bearing hub I'd be surprised to see the two sizes of flats, and that part would usually be aluminium. As for the locknut, it looks very much like the thick ugly ones you find on cheap loose-ball hubs that are knurled on both sides, and yeah - they can be pretty tough to crack. The two-wrench solution is a good one. If you don't have a second 17mm or a vise, an adjustable wrench works fine if you know how to use it.

The best way to crack hub locknuts (and cassette or disc rotor lockrings) is to have the wheel on the ground against your legs with your tools at 3 and 9 o'clock and after ensuring your tools are properly engaged and aligned, a quick, precise shove almost always does it. I'd be surprised if you'd damage a quality cone wrench with a good enough technique.

Another way that can work is arranging your tools nearly together so you can squeeze them together like pliers, but this is more likely to involve misalignment and mashed tools and parts.