If it does nothing but behind the scenes work (and some attempt at blocking piracy), I
seriously doubt they're going to announce it at E3. All it would take is a single reporter that isn't a nintendo fanboi to laugh them off the stage.
Just imagine it:
nintendo representee: hi. I'm pleased to inform you all that we're going to update the firmware of our flagship, the wii, to a whole new version.
journalist: interesting...that would bring it to 5.0, right?
nintendo representee: indeed.
journalist: so...what changes can we expect?
nintendo representee: it'll be mostly fixes. But other than that, we're looking into optimizing internal processes,
blockingsomepirates and streamlining the code. We want to make sure we're giving the best experience to our customers.
journalist: so...basically the same as 4.2, right?
nintendo representee: well...yes. But since then, we found a couple bugs here and there.
journalist: really? Crucial ones?
nintendo representee: not crucial in the sense of things going wrong. But rather essential in terms of optimizing.
journalist: isn't that the same thing you said for 4.2?
nintendo representee: well...yes. But optimizing isn't something you do overnight. It takes time and effort. We...
journalist: but there won't be any new features?
nintendo representee: no. But nonetheless, we strongly urge our loyal customers to update, because under the hood, we've made some very interesting changes for them.
journalist: I've talked to your "loyal customers". Do you know how many noticed anything different between 4.1 and 4.2?
nintendo representee: we've attempted to make the update as non-intrusive as possible, so...
journalist: no one. From the hundreds, maybe thousands of people questioned, not a single one noticed any improvement.
nintendo representee: well, if they had a stopwatch, they would have seen it.
journalist: on the other hand, there were a few cases of wii's becoming corrupt after that update.
nintendo representee: those were mostly pirates.
journalist: I'm not talking about pirates.
*a few seconds of deadly silence*
nintendo representee: euhm...of course we regret certain circumstances where, in the event of a failed upgrade, a wii may indeed become corrupt. But really, the chances of that happening are...what? One in a thousand? One in a million? I can further say that we've provided these unlucky persons with brand new models.
journalist: indeed. But it does raise the question: why would people want to update to this new 5.0 if they can't see any improvements to it?
nintendo representee: euhm...well...euhm...I'll have to give that question a thought. Can I come back to this later?
journalist: sure thing. But in the mean time...do you mind if I share this conversation to the entire world?
nintendo representee: ...
nintendo representee: *runs for cover*
...damnit. Now I want to be at that convention
just in case nintendo decides to unveil a new firmware.