The change doesn't necessarily spell trouble for Oculus or Facebook's overall VR efforts, but it does continue a trend of constant shake-ups in leadership. Barra took over in early 2017, shortly after Oculus co-founder Brendan Iribe stepped down from running the team to take on a more specialized VP role. Not long after, co-founder Palmer Luckey left Facebook following a row over his political actions. Iribe himself would go on to quit Facebook in October 2018, reportedly due to corporate upheavals that included a shift away from high-end PC VR and toward mainstream stand-alone headsets like the Oculus Quest. Even with Barra at the helm, then, there hasn't been a huge amount of stability.
Whether or not this change will affect Facebook's plans isn't certain. In the short term, you're not likely to see much difference. Oculus is just about to ship both the Quest and the Rift S, and Facebook already outlined some of its upcoming AR and VR strategies at its F8 conference. It may take years before Barra's exit (and Tseng's arrival) have a meaningful impact.