Canon will have to update their 16-35II and perhaps even the earlier version-one L primes...
It is clear they are having difficulty delivering on the UWA front... it is certainly not for the lack of trying. They have tried with version II which is, as I said elsewhere, "meh".
The 16-35 was (I read a canon comment a few years back) introduced for PJ's using the APS-H cameras. The MK II was a attempt to upgrade it for FF.
Canon knows how to produce a top quality wide lens, but they have not figured out how to make one that ordinary millionaires can afford.
You see that with other products as well, some car companies are good at making large cars, but are utter flops at making small cars. Some small truck makers have flopped in the full sized truck area.
Its not easy to overcome that type of thing, some highly experienced employees don't always want to change their rules of thumb for design, and they pass down those rules and keep new employees under their thumb.
Nikon suffered from that until some younger blood finally got to the top. The trouble is, they also need to make a profit. Innovative ideas do not keep a company in business if they don't turn a profit.
Nikon is building a giant plant in Laos to open this fall, apparently hoping to ultimately get their costs down. They also (I think) understand that the warmer weather means more floods and they need to have plan(t) B. I hope it works out for them, lower prices are certainly welcome, and Canon is in the drivers seat right now as far as cost of production is concerned. They drop prices and still make a nice profit.