Satsuma has always been an interesting case; she's strong proof for the proposition that all the attributes we associate with the dreadnought revolution were coming, and coming soon, with or without Jackie Fisher. But Fisher certainly made it happen more quickly and more dramatically.
The real question, though, is whether Satsuma would have qualified as a dreadnought even in her originally planned configuration. HMS Dreadnought had a number of revolutionary and evolutionary developments in her design (@Driftless mentions the centralized electrical fire control, for example), but the two which are most commonly identified as qualifying her as a new capital ship type -- and the eponymous one at that - were 1) an all big gun gun main armament, and 2) higher speed machinery, usually achieved through turbines. The point of Dreadnought was that she could outgun any ship in existence, and chase them down if they ran. At least, until dreadnoughts with even bigger guns and even faster machinery got built . . . But the point is, Satsuma would only have had one of the two dreadnought attributes: (1) all big guns. And even so, even this proved to be too expensive for the Japanese treasury in 1904-05. That is hard to overcome as a point of departure.
The same problem is evident in the U.S. South Carolina class. The South Carolinas actually *did* follow through and commission with an all big gun armament. But as with Satsuma, they kept a traditional triple recriprocating machinery that limited them to the typical pre-dreadnought standard 18.5 knots, which ended up making them obsolete very quickly. It's also why they're often considered (like Satsuma) only "semi-dreadnoughts." It is interesting because fundamentally the United States went in this direction for the same reasons: 1) the budget was limited (albeit more by Congress than U.S. economic means), and 2) U.S. naval officers shared with Japanese a higher priority on range and sustained operation over the vast distances of the Pacific. Jackie Fisher's battlewagons were mostly just being asked to cross the Channel, the North Sea, or the Mediterranean.
On the whole, I think the United States makes for a more plausible contender to beat the Royal Navy to the punch. Fundamentally they had the *means*; what they really lacked was the will. As it was, Teddy Roosevelt (following on Poundstone's paper) was what broke the political logjam to get the South Carolinas pushed through; with a little more energy, it is not unreasonable to think that he could get the money to ratchet up the tonnage limit enough to put in turbine machinery. And this could have had quite the interesting impact on Anglo-American relations at that juncture, to say nothing of Japan.