Yes. Through accidentally misplaced wallet keys, death, natural disasters etc.
And that even one day, all of bitcoin may be lost?
Possible. I don't foresee that ever happening though. For this to happen, everyone has to collectively either burn or lose their Bitcoins. It could happen after 2140 but you can be sure the more scarce Bitcoin becomes, the more careful everyone is.
Losing Bitcoin would just decrease the total supply and theoretically making every coin more valuable. There really isn't a negative effect to Bitcoin in general.
Is there a way to recover them in the future? A possibility could be helpful because this will be really happening and it will go like a thief in the night. It just feels scummy for me that the more bitcoin lost in the cause mentioned above when there could have been ways to prevent them.