My teacher made a few points in connection with this. Now that I got to this point in my own practice I'm beginning to understand what he meant.
When the illusion of self is lost... motivation that animates most people is no longer there. There's no impulsion to engage in projects or entertainment activities. Projects may seem meaningless and entertainment - empty. This makes it hard to relate with people. Buddha said, the mind of "one like this" is inclined towards seclusion. This does not happen overnight, but develops gradually. When this starts happening to you - do not freak out. This is normal. There's nothing wrong with you. On the flip side, you may find yourself enjoying nature a lot more than before. Enlightened mind goes well with nature, so don't hesitate to spend more time out in the wild.
Nevertheless, sometimes there may be sudden longing for "normal life". You can try it if you want, but be aware: at some point you won't be able to play samsaric games anymore, you just won't function the same way as before. There are anecdotes in Buddhist tradition about people going insane trying to fit back with the normal. Don't force it. It's okay to be different.
At some point you may start worrying that you don't know what to do with your time. My teacher said, it's best to follow your instincts, listen to your heart. Once you develop enough connection with Bodhicitta through meditation and no-self, your instincts purify, they no longer come from egoistic impulses, so you should trust them. If you feel like not doing anything, or even taking a nap - it's perfectly okay. Eventually you get sensitive to reality giving hints and inviting your participation. My teacher said, when enlightened activity is liberated from pressure of judgment, it becomes spontaneous and creative. There's no need to push that though, it comes from your suchness and inner peace.
You may find yourself having hard time sleeping same number of hours you're used to. The thing is, you don't have to sleep same hours anymore. As you integrate with your "other mind" your brain no longer requires as much sleep. Don't force yourself. When you do sleep, you may have strange dreams: walking through walls, staying lucid inside dreams, and other weird things. Don't worry about this. Some of it may be good signs of the changes going inside you, and some is just noise. Trust your instincts on what's what.
At some point you may stop recognizing yourself in a mirror. Don't worry about this, you're not going insane.
In general, a good rule of thumb is to "leave your mind as open as the sky, but keep your action as pure as the flour". Meaning, as long as you don't engage in immoral uncompassionate action (physical, verbal, or mental), you can relax and let your selflessness drive.
Finally, all my teachers said, at some point you are supposed to naturally and effortlessly get over this highly polarized selflessness/seclusion phase and reach the level when there's no difference between your meditation mind and the mind you have when walking in the busy marketplace. At that point you can integrate both worlds, your regular mind is meditation and your regular action is setting example of peace to everyone you encounter. As with all this stuff, pushing it is counterproductive, it has to grow by itself from the full maturity of the selflessness.
These are some of the main things that come to mind. Some of this I know from my own experience, and some only from words of my teachers, but I hope it's all accurate and is helpful to someone. Good luck to us all.