I don't think there was a chance of a Spartan anyway. Yamato expressed that they weren't interested in it and they were just going to do the three that shared parts. So if the chances of the Phalanx was slim, the chances of a Spartan was always nil. But then again they said that there was going to be no Macross Toy. So maybe we can expect a $275 Spartan....
1/60 is without a doubt the definitive scale. With all the Yamatos available from SDF, DYRL, MacPlus and Mac Seven, Mac Zero and yes Bandai is producing Macross Frontier valks in 1/60.
The nearest thing to the 1/60 scale will probably be the 1/100 scale but it's still unknown what Bandai's future plan with that is. But they have produced the VF-1, the VF-19 and will have the YF-21 upcoming. Add the 1/100 Koenig Monster from both Bandai and Yamato, it seems to be building up as the alternative scale. Line is cancelled I believe.