For my day job I’m writing a renderer that runs on WebGL 2.0 via Emscripten’s automatic translation from OpenGL ES 3.0 to WebGL 2.0. WebGL is impressive for a browser, but it’s got significant overhead compared to raw OpenGL. State changes are quite expensive and had a very noticeable impact on our renderer’s performance.
As far as your concern about relying on OpenGL… forget it. Practically everything has OpenGL these days, and every platform you’d consider releasing a game on certainly does. jME depends on OpenGL 2.0, which is ancient history. I’m not sure of exact numbers, but I’d bet good money that a huge portion of machines in use today support OpenGL 3.0 or even OpenGL 4.0+ - both of those are fairly old news in the OpenGL spec history. If a device is significant enough for you to consider supporting it for publishing games, I 100% guarantee you that it has OpenGL support and probably support for much newer OpenGL versions and features than jME needs (even the Raspberry Pi has OpenGL support, and it’s hardly a big target for game publishing).