1. Virus epidemic is still not possible on Linux
Nobody is going to care about making Linux popular until it is possible to spread viruses and trojans on it widely.
2. No nice antivirus software for Linux Desktop available
As viruses are not popular so antivirus companies do not care much about creating something good for it. What a user can trust a system without antivirus?
3. Migrating Linux to new hardware is too easy
Moving to new hardware is as simple as moving your disk drive to another system. No reinstalling software, no reconfiguration, no driver installation. How end-user support companies are going to make money on this? Thus they do not care about making Linux Desktop popular either.
4. Most of software is in on place and freely accessible
There is no software company which can keep users and make them pay without vendor lock-in. Possible with Linux? Absolutely not.
5. Spying on users is very difficult
How can companies inject spyware or adaware while most of software are coming from a distribution repository? There is on easy way. No companies like this.
6. Linux is too customizable
The more freedom to users is given, the less control of them is taken. Less control means less money. No, users do not need freedom.
7. Deep look inside is possible
Allowing looking inside is way too dangerous. What if advanced users can find some stupid bugs? What if the can fix something by themselves? What if they can copy our ideas and user them in their own projects? Users should not have access to source code and modify it. They should not even understand how it works until they purchase for a related course.
8. Encryption out of the box
Many of Linux distributions provide strong system and profile directory encryption out of the box. Neither government nor companies are interested.
Is there anybody who still think that Linux is ready for Desktop after all this? I doubt it.