https://wccftech.com/valve-would-like-to-continue-pushing-half-life-series-forward-after-alyx/

Half-Life fans are overjoyed today after the unveiling of Alyx, the VR installment confirmed by Valve to be due for release in March 2020.

Perhaps they'll be even more excited to learn Valve has plans that go beyond Alyx. Speaking to The Verge, Programmer/Designer David Speyrer (whose credits included Half-Life 2, The Orange Box, Left 4 Dead, and Left 4 Dead 2) revealed as much while discussing Alyx.