Again, speculation is fine as long as it's not passed as fact...

I like the performance that I see exhibited on the Exynos. Particularly the GPU fill and shader performance. But I will be the first to admit that this is mainly ignorance as a comprehensive performance measurement tool is somewhat lacking, and the playing field is not even between devices as to accurately ascertain performance.

Yes, the texture format (specifically textures with an alpha channel) is an issue for developers, and Tegra has tegra-zone, but as you alluded to, one of the likely best selling devices this year, the Galaxy S II, is packing the Exynos 4210 w/ Mali400mp, and you can bet that it will have an increasing game selection as time goes on. A popular devices is a good incentive to support Mali.

I bet that the Galaxy Tab in whatever incarnation it comes in will be popular as well. Again, great incentive to 'port' your games.

I don't think that Tegra's early success is enough to write off other SoCs and their GPUs. Besides, diversity in this space is good.

By the by:
AFAIK, texture compression algorithms are one of those annoying non-standardized aspects of GPU design. GPU vendors tend to have their own intellectually-protected formats. I don't think a better driver would cut it.

ETC1 being standardized by Khronos (ES2.0) was a great move.... but they left out the alpha channel with that format, which is a boneheaded move. Since transparent textures are pretty common, this leaves vendors to choose their own formats, and low and behold, they are all different.

A smart developer can work around this in any number of ways. One way would be to use an ETC1 compressed layer that represents the alpha and blend with the original texture using a shader to provide transparency. There are memory tradeoffs with this technique, so it would be highly dependent on the amount of transparency in the scene. Of course, innovation doesn't seem to be the strong point of many, so this is likely an unrealistic expectation.