In Short: While responding to a question on Twitter, Google has confirmed that the new gesture navigation in Android 9 Pie is the only navigation option for the Pixel 3 and Pixel 3 XL. That's not all, though, the company also said that this new pattern "will represent navigation on all Android phones going forward", which basically means that Google plans to do away with on-screen buttons altogether. Well, the company basically did that with the Pixel 3, but it seems like it will push that others do the same. The beauty of Android is having options, though, so don't expect other Android-based phones to be limited to Google's new navigation bar, as Samsung has its own navigation-based philosophy, same goes for Xiaomi, and OnePlus, for example, though OnePlus gives you an option to use Google's navigation as well, if you want (in Android 9 Pie).
Background: This was Google's answer to a question from a user called Chris Bohannon, who asked if the new navigation bar can be disabled, and replaced with regular buttons, as users can do on the Pixel 2 and Pixel 2 XL. Google has received mixed reactions to its new navigation bar, it seems like users either love it or hate it, but it's surely not a reaction that the company expected.
Impact: Google's new navigation bar is more complicated than both regular buttons and most other gesture-based navigation solutions out there, not to mention that it combines gestures and regular taps, which seems a bit odd to most people, even comments on Google's response are mostly negative. Many users mentioned that Google's new navigation bar seems like a work in progress, rather than anything else, but it seems like Google will stick to it. More or less everyone expected Google to opt for a purely gesture-based navigation before the company introduced Android 9 Pie's navigation bar earlier this year, and it remains to be seen what will happen from this point on, and if Google plans to adapt this new navigation bar in the near future, though that's highly unlikely.