If you're talking about physical buttons, please no. Gesture navigation is an incredibly useful feature for those with short fingers like myself, who have problems with reaching the "Recents" button without weirdly tilting the phone and then stretching their thumb to the point that it gets painful over time. And while it's technically possible to use gesture navigation on phones with physical buttons, it would definitely be weird. Not to mention that it's also wasted space, because physical buttons obviously can't just disappear when needed like on-screen buttons do, so you can have a bigger and more efficiently used screen. There are a lot of things that are dumb to remove from phones, pyhsical navigation buttons, in my opinion at least, are not one of them. I can't even think of an advantage physical buttons would have over on-screen buttons.
If you meant that you want to keep the option for on-screen button navigation, I'm all for it. Can't hurt to have more options :)
I don't think this is a common use case for most people, but I can see how that might come in handy for some, so you've got some good points.