Is the boss's job at risk?

My two pennies are that there is only one reason for bosses to fire people in corporate world especially now: to keep his or her own job. If you keep an income for someone by offenses, it is not pleasant but still tolerable within this particular market. It seems that your boss is having some personal issues and he is trying to convince him/herself losing you may be a solution, but he is not sure yet.

Figure out what you can do to keep both jobs--really you and your boss share one job. Meanwhile, if he or she has insinuated your termination without HR presence, that sounds like blacksmith.Document confirmation with his signature/comments and be ready to protect yourself. It may never happen, but this self protection may help you see things in perspective.