I see what you're saying, but my point is that you cannot reasonably make this deduction. Pete's statement was generic, not specific.
I can see how you could call that generic, and in a way you'd be right, except... well, I'll get to it later on in this post.
You are inductively attempting to derive something specific from general/broad data. It's like deducing that since GM makes cars they're going to come out with a brand new sports car next year called the Corvette 2.0 (however we cannot know this only from the initial premise).
...for this being a bad comparison. Hines doesn't say: "We're working on a game" from which I deduce they're coming out next year with TES V: Skyrim. He actually is quite specific with brands GM is currently working on. He says what would the equivalent of "Our team has its hands full working on the latest Chevrolet [[of which we're about to sell our latest upgrade]] and on the Buick [[which had its last sign of life years ago]]."
I would agree with that it's a general statement if he said: "Todd's team still has other big titles such as Fallout and The Elder Scrolls to think about". But he doesn't say that. He doesn't make a passive statement. He instead makes an active statement: "They're
busy with Fallout and Elder Scrolls", which puts the described situation in a whole different light.
This is the deduction:
P1: Todd Howard's team has their hands full on TES and FO.
P2: "Having your hands" full means to be actively involved with something
P3. Todd Howard's team is a team of developers.
C1: From P1, P2 and P3, Todd Howard's team is actively (P2) developing (P3) FO and TES (P1).
P4: TES IV had been out of the development cycle for years.
C2: From C1 and P4 the DevTeam was at the time not actively involved on IV.
C3: From C1 and C2, the DevTeam was at the time involved with a new TES.
But, as you say next, ...
In our case it just so happens to most likely be true that TES:V is being developed, based on other circumstantial information (book gaffes, trademarks, etc.). Keep in mind, however, that we don't know this with absolute certainty and that Pete's comment does not provide certainty; it only gets us from about 95% certainty to 95.1% certainty but that's about it.
Indeed, it doesn't provide any more certainty than we already had. At this point we're pretty damn sure and this is just lost in the sea of clues we have.