Even holding market share is not enough
Intel really do look like they have their backs up against the wall with huge competition for ARM-based devices.
Even if Intel can pull off the unlikely and keep up market share, that is not going to be enough. ARM parts cost a lot less than full-fat Intel parts. To compete, Intel will have to be selling a lot of Atom parts making a lot less profit per chip.
Intel are a company built around very high margin devices and re-gearing a company to survive on low-margin chips is hard. They might be able to get there in the end but it is going to be painful and Wall St is going to punish them.
What is sad is that Intel were in the game with their XScale ARM-compatible parts. If they threw all that process magic they are using on Atom at XScale they would be in a far better position.