Yes, it definitely would make sense to have a BBC One, Two and Four without a BBC Three.
Which is the situation we're currently in. BBC Three is just the name of a strand of unrelated programmes that sometimes get broadcast on BBC One, but often just get left online. Bit like BBC Sport or Inside Out. It's certainly not a channel.
"Just get left online" as if no one watches telly on the internet.
To be fair though, you could get away with BBC Sport as more of a service online anyway, since you've got tons of articles and videos regarding sport and it has it's own purpose as a website/app.
BBC Three? At least with Sport you've got a whole variety of content but from looking at the Three website at a glance, does it really make me want to "scroll down"? It just looks like a three-panel shop window that brings me to iPlayer anyway, what was the point of relaunching the BBC Three site when all the other channels don't have their own dedicated pages anymore and don't need one?
A lot of the articles on BBC Three are things you could easily get away with placing on the News site instead. These articles don't exactly compare to an entire broadcasting stream, so do these articles need to be neccesary when these sort of things are already done by the BBC and better for it's audience? I don't see anyone talking about BBC Three's "successful" journalism, nor do I see BBC Three winning awards for news-related articles, it's mostly its own programming.
Do you even read these?