This doesn't really make sense. Capcom has always had multi-platform Monster Hunter titles.
Yes, but not competing attempts at the same basic product on comparable platforms. There's only one platform that got a developed-for-handhelds MH last gen (PSP), and only one platform that got a developed-for-consoles MH (Wii). Then there's an MMO (on PC and 360, because those are the places they could negotiate the deal they wanted for subs) and a bunch of random iOS crap. None of these are substitutionary goods, whereas competing 3DS and Vita series would be.
Basically: if they were going to spend time developing two different series, why do it on 3DS and Vita (which target the exact same market and have the same lifestyle benefits) when they could do it on, say, 3DS and PS4 (or Wii U, or whatever) to have one portable and one home-console series?
What else will they do with the Portable brand?
There's no such thing. If MHP3 had been called "Monster Hunter Three" instead it would have sold exactly the same number of copies to exactly the same people. It had no brand meaning on its own except as a convenient signifier of the difference between the console and handheld releases.
So let's say Capcom is foolish enough to only make big MH titles for the 3DS. With the route they're going, they'll oversaturate the market quickly.
Like... they did... with PSP? Lulz.
I've seen this a couple times and don't really understand it. Why would releasing a game on two competing portable systems (MH) hurt sales, but releasing a game on competing consoles simultaneously help sales for the publisher? Isn't it the same thing? One game on more systems will bring more sales?
Monster Hunter is a franchise whose appeal lies almost entirely in
local co-op multiplayer. As a result, a multiplatform release is actually worse for players, because their local group of potential players will be split and everyone will have a harder time finding co-op partners. The same concern doesn't apply to single-player games (where it doesn't matter if anyone else buys the game) or online games (where as long as each system sells a decent number of copies there will always be
someone to play with on each platform.)
It wouldn't be such a problem to release
different games at different times on the two systems, since then buyers would be secure in the knowledge that everyone buying the latest release would be intercompatible, but the question is... why? There are almost no publishers in the industry who actually engage in this kind of release pattern, because there's not much point to it. If a series is successful on a given platform, there's not much reason to put resources into a lesser-selling iteration on a similar platform when you could invest elsewhere (home console version, other franchises, etc.)