I very much doubt that any one entity will ever have 50% of the computational power. The botnet operators will bow to the whims of the community because it's the community that ultimately gives bitcoins value. What good is a giant load of bitcoins if you don't have anyone willing to give you something in exchange for them?
If Satoshi starts enforcing a maximum transaction fee (as he's
mentioned) and the limit is too low, no one who is generating for profit will "upgrade".
Changing any parameters in a way that reduces profit for generators would have the same result, I think.
I was thinking this is a nice thing about bitcoin. Only a majority is required for an attack, but you need even more than a simple majority for a smooth rule change (only for certain kinds of changes I realize).
I agree. The current economics are perfect, and it would be very difficult for anyone (even Satoshi) to make a major change.