A(nother Dumb) Theory as to Why VALVe haven't mentioned anything of a Half-Life 3

Yes, I know, the internet is awash with about fifty gazillion theories as to why Valve haven't mentioned anything regarding "Half-Life 2: Episode 3" or "Half-Life 3", but the other day, whilst playing back through Portal 2 for the fourteenth time, something occurred to me that hadn't before.

Valve have a very distinct style in their games. Okay, sure, they're all just first person shooters, what's distinct about that, right? I mean, whilst franchises like "Call of Duty" have forgotten what makes a game a game and have just started churning out sequels like there's no tommorow are clearly doing it all for the money, the titles released by Valve still keep up with the quality of being completely state-of-the-art, at least in terms of the Source Physics engine, as well as being designed so that the gameplay is fun, even to play multiple times over, (or, in the case of Team Fortress 2, keep playing at all), and, most notably, they keep the storylines deep and engrossing; the main reason most of us want to see a finale to the Half-Life series is to find out whether or not Earth will be liberated from the Combine, who the G-Man is, and what the flipping heck the Vortigaunts are supposed to be rambling on about when they mention nonsense like "The Vortessence" or whatever it is they're trying to say. I mean, there's little more iconic in the gaming industry than the Black Mesa logo, a lambda symbol, or even just a crowbar. The original Half-Life is said to have revoloutionised gaming by being "realistic", in as much as weapons, health and ammunition were found lying on tables or in cabinets, rather than as spinning icons in the middle of the room. These days, that sounds fairly basic, but at the time, it hadn't really been done before.  This, amongst other things the Half-Life franchise have brought to us gives the franchise a lot of reputation in the industry, and Valve know it. The problem is, in recent years, overcooked franchises like "Call of Duty" have been selling more and more, whilst games with proper storylines or ingenuitive gameplay have been cast into the shadows........ except Valve games.  But I think that Valve are afraid that if they release Half-Life 3, then everyone will stop paying attention to them, and so don't bother even mentioning it, in the hopes that everyone will stick around simply in the hope that a continuation to Half-Life will be mentioned, and that when it isn't, they'll buy Valve's other games so that they have something new to play in the meantime between then and the announcement of the next Half-Life game... which if this theory is correct, won't be announced.

So, to summarize for those of you who were daunted by the big paragraph above and scrolled straight to the bottom, Valve are leaving a popular series unfinished, simply to make sure their eager fans keep listening to them and keep buying their stuff in the fear that if they do finish that series, people won't care about them anymore.