[3.5] Would these changes be enough to T3-ify a Druid?

[chaos_redefined]

Just use the shapechange ACF for wild shape. Take away natural spell, and you should have no problems with letting them have full casting.

animal companion could just be a summon... like they can use a slot of their highest level to summon the animal companion for CL/minutes.

Assuming you mean the one from PH2, I personally find that ACF insulting. It gives you the buffs from the various bite of the X series, at the cost of your equipment and your animal companion (and wildshape/natural spell).

In any case, if you wish to use it, then it already loses natural spell anyway, since they no longer qualify. If the option was this or the above, I'd probably take this and never use the shapeshift (full casting > weak animal companion+wild shape).

Generally speaking, I generally hear the following as a simple method of fixing the druid (although I don't think it goes far enough...)

Lose one of the following: Animal Companion, Spellcasting or Wildshape. This ability can not be modified at a later date.