The PS4 can regain its marketshare if they release a console before the new xbox/wii

Loyalty is an illusion, brand loyalty doubly so. Only a very easily influenced person will stick with an entertainment company that's failing when they're aware of better options, which is rather why Nintendo's "massive audience" from the NES (and to a lesser extent, the SNES) did not carry over for the N64 or GameCube. So don't expect brand loyalty to "save" the PS4 any more than it's "saved" the PS3.

As for if Sony can regain a position of dominance with their next system, that's very much hard to call. The wildcard is what Nintendo does, as their decision for the next generation of systems could easily make any effort short of a coincidental parallel to their decisions from the competition end up being moot. Neither Sony nor Microsoft shows any interest in actual innovation, so I don't expect Sony will be pulling a Nintendo and actually revolutionizing gameplay with the PS4; more likely it will be a souped-up PS3 with Wii controls (much like how the PS1 is a souped-up SNES with CDs and memory cards, and the PS2 is a souped-up PS1 with analog and rumble as standard features).

If Nintendo spontaneously returns to the methods that Hiroshi Yamauchi favored (that of producing a successor like the SNES or N64 instead of a new system entirely ala Wii and DS), then Sony will have an excellent chance of reclaiming the industry. Let's be honest, Nintendo does not do the hardball game well when their competitors are made of money. But if (and this is much more likely) Nintendo turns the industry upside-down again with a total curveball of a system that makes even the Wii's gameplay style look outdated, then Sony will be in trouble again.

Although I don't disagree with most of what you're saying, I still think Nintendo has an advantage going into the next generation even if all consoles are (in essence) a souped-up Wii.

The one area where brand loyalty actually exists is that consumers are likely to continue buying a product in a brand that they're familiar with as long as there is no strong reason to change their buying habits. In the videogame market, I suspect that if you're entering a generation where all consoles are (essentially) the same the console that was the market leader in the previous generation has a massive advantage; to a certain extent, this is why the PS2 and SNES were so successful in their generations.

Yes, there is something to be said for inertia. However, there are also a few characteristics of the SNES and PS2 that gave them an edge in an otherwise equal playing field. Most notably, their game libraries quickly got a reputation for being home to a great deal of excellent titles of all genres, while their competitors only had a fraction as many must-play games. Brand loyalty did help a bit, but ultimately, the main driving factor in the market at that point was the plethora of games that suited multiple tastes. When the interface is near-identical across the board, the software quality and diversity takes on ever-greater importance.

That said, I'm sure the massive third-party support showing we'll see for the Wii by the end of this generation, compounded with the massive first-party support, would essentially assure the Wii's successor a head start against its competitors even if it was just a Wii HD.

No

mayhap.

^you failed. I'm going to assume you meant "may happen". It is way to similar to "might happen" :-p