You need to quantify what you consider "good enough" in order to answer that.
Second, in more relaxed terms of bandwidth, when do we reach "enough" so that even revolutionary improvements don't really matter any more? Do I really need the ability to download a full 4k movie in under six seconds? I don't mean that as a "640k should be enough for anyone" argument, but at a point in time, yes, 640k did count as "enough" for most purposes, even though at that same point in time we had supercomputers with a whopping 16MB of main RAM.
Doesn't your first statement really answer that?
What we have is already "good enough" for everyone... if all everyone needs to do is communicate in near real time. But we can make use of more. And we will probably always be able to make use of more.
If we want higher video resolution, more video streams, futuristic smell-o-vision, and internet-enabled cyber-robot sex, we'll ask for more speed. When that becomes commonplace, but we want to be able to exchange DNA sequences on dating sites, then we'll need more.
I think, when it comes to technology, everyone has it backwards. Supply drives demand.