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.
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.