What’s the next target for Ukraine here? Obviously they’d love to cut the land bridge and put pressure on Mariupol but is that at all feasible?
There's a lot of options actually, altough I would say there's 3 fronts to focus on:
1) The path to Crimea. It basically starts by retaking Nova Kakjovka, which can now be reached by HIMARS at any moment. Once there, the water supply to Crimea can be cut anytime, forcing the RA to choose between a risky action or to be slowly weakened and eventually defeated.
2) Zaporizhzhia/Melitopol. It's maybe the hardest and the one that's gonna be more brutally defended by Russia. Melitopol is basically the hub for all of the RA logistic operations in the south, even more so after the sinking of the Moskva and the damaging of Kerch's bridge.
3) North Lugansk. Here the equation is simpler: it's supposedly the region worst defended by the RA. Its activity also helps straining Russia's logistics from the Dnieper to its own (real) frontiers.
We should also consider the bleeding of Donetsk front (specially at Bahkmut) as an attrition factor for both sides, altough not that crucial strategically speaking.