It must mean that ARM are pretty impressed with Keil's tools, since Keil's tools are only a couple of years old, and ARM already has their own well-established and well-regarded tools.

Of course, ARM's ultimate goal must be to sell more ARM cores. The press release (and Reinhard Keil's comments) say that they see this as a way to ease the path from 8- and 16-bit to ARM.
If that's really the case, it would seem essential to the plan that they do keep the 8- and 16-bit tools in good order.
We can but hope!

It does seem to be consistent with their stated aims when they tried to buy Triscend - shame that Xilinx scuppered that one! :-(

And it's British!