What does “what’s in store” mean?

I saw this sentence today as the motto to a meeting of English teachers:

What’s in store for us teachers?

Although I think I can grasp the meaning of this sentence — something like “what is being kept for us?” — I can’t understand what it means when used in the song “I get along without you very well”, as made famous by Chet Baker:

What a guy! What a fool am I?
To think my breaking heart could kid the moon.

What's in store? Should I ’phone once more?
No, it’s best that I stick to my tune.

So — does it just mean “what is being kept for me?” or does it have a more idiomatic, nonobvious meaning? As a bonus, if anybody knows what is “stick to one’s tune”, please let me know.

Solution 1:

"What's in store?" means "What's going to happen in the future?" rather than "What is being kept back?" Sometimes there is an implication that the things "in store" are planned by someone, but not always.

Edit: I forgot about "Stick to my tune." That is a piece of poetic writing which takes advantage of being part of a song. "Stick to" here means "keep to" or "stay with" in a metaphorical sense; the lyricist is saying that he should carry on doing what he normally does (his "tune" in this metaphor). It's more commonly found in phrases like "Stick to your guns".

Solution 2:

It usually means 'what does the future hold?'. Maybe 'what's going to happen?' It often refers to the more immediate future but not necessarily.