If I were a betting man, I'd put some money on them working more on the rear end for now, I think they're more or less happy with how the front end of the car is working. Taming the rear is and has been the focus since winter testing, and also the more expensive side to get right, because that's where the power unit resides. Because of this, it's also the side that has the highest lead time as far as making improvements.
Question is, would there be any benefit to making a slimmer Mercedes/McLaren style nose?
One thing I noticed, is that Red Bull and Mercedes have a very similar approach to the front wing, especially on the under side, but Red Bull goes for more flap near the end plates. They try to keep the high flap angles by the radius on the upper outer flap to try to coax air to outwash. It's made some improvement, but there is still refinement needed to the geometry to get it to perform exactly the way the want it. They may need to compromise by having a little less angle on the upper outer flap to get the balance perfect, or rather improve the geometry.
Another unique thing I noticed on the Mercedes is how the Y250 side seems to have a pair of vortex tunnels.
Ferrari does it as well, as far as I can see these two teams are the only one's doing it.
McLaren certainly has an interesting take on it. Placing the vortex tunnel in the middle of the wing along the strakes, very interesting.
By contrast Red Bull seems to focus on getting the vortex tunnel to induce outwash.