At some point, native would still be faster in the same sense a curve approaches the x-axis but never quite touches it.
The mobile web rendering performance might never hit the 0-grade latency standard where we put native, but it will eventually get so close to it as to not make any difference whatsoever to anyone but cold-hearted scientists the likes of whom whish they could keep their science drinks at absolute zero chilly bins.
HTML hit practically 0 latency 10 years ago then we added DHTML, CSS, encryption, Ajax, 3D, multitasking, 2x DPI and 4x screen size, background syncing, ...
When will we stop adding functionality to soak up the hardware power?
If we hadn't added those things, HTML&Cia. wouldn't even be a contender to replace native performance now. It would still be a simple technology meant for static information.
If your argument is more in the line of why do games keep getting bigger and meaner, needing more resources, when we could have stopped advancing 3D a decade ago and every computer would be able to play any game today; then that's a whole other discussion. But I like the path towards true virtual reality with photorealistic graphics.
The mobile web rendering performance might never hit the 0-grade latency standard where we put native, but it will eventually get so close to it as to not make any difference whatsoever to anyone but cold-hearted scientists the likes of whom whish they could keep their science drinks at absolute zero chilly bins.