That's gonna cost Apple in the hardware end, but it will likely mean that their operating system can be ported to other computers, namely PC's. That will threaten Microsoft, cause Apple actually has a working product that a significant number of people use, and a decent amount of high-end software is available for.
On the downside, the quality of their processors is gonna go down. The reason Apple is the product of choice over the PC for graphics users is the fact that their processing power is so much greater (even though the clock speed is lower, the amount of data that can be crunched is massively better)
As a Mac user, I'll likely be purchasing a PC in the future and simply running Mac OS on it, instead! (the hardware is cheaper)
"A bad carpenter always blames his tools!"
- Grandpa Boris
Make war, not love! It's safer!