IP providers like ARM will work with all the leading foundries. (right now, TSMC & GF) They definitely would not exclude a top foundry.
I'm sure ARM will have tight restrictions on information sharing between those projects.
It would be significant if they also do something similar with Samsung.
I really hope there is room to other competitors, ARM has build an impressive portfolio and a collaborative environment, however, the customer will lose in the long run without real competition to ARM. Same argument is valid for TSMC and GFI as well.