I think you're trying to ask if the bubblenest is permanent and/or if your Betta will feel threatened with other fish approaching it? I don't think a Betta in a community tank would feel comfortable enough to build a nest, IMHO, unless he has established an area of the tank as "his". If he does build a nest, yes it will go away, and he'll probably keep building on it if he's happy! A bubblenest is self-explainitory - it's a cluster of bubbles, nothing more. There are no eggs in there (if, hopefully, you are not keeping a female with him) so he really has no reason to guard it. All Bettas have different quirks though, so just keep an eye on him.
BTW, Toki, your Betta is adorable! I love orange boys... he looks very happy ;0)