Yes, the nostrils really looked like a compromise, a quick way to add air volume underneath the car without having to design completely new and expensive crash structures.
Basically everybody, even Ferrari and Mercedes will eventually try to move to the minimum dimensions of what both Williams and Red Bull have:
The thing is that it while it is a clear cut & low compromising solution (it does add a little bit of drag though), the extra performance it brings is not all that big. It is costly too; Williams had to compromise the chassis and Red Bull really had to push their engineering capability to make such a short and angled nose get through the crash tests.
However, they will eventually all converge to this point. If not this year, then in the following years.