It is safe to drink warm soda although the warm soda will not usually taste as good as cold soda.
As soda gets warm it can tend to go flat and not be as good but it's still safe to drink.
Hot soda is not as good either but still safe to drink.
Although if your soda has become hot or warm it's best to refrigerate it and let it cool back down before drinking it so that it tastes better.
I've drank some warm soda before and nothing bad happened although it was just not as good.
Carbonated drinks tend to lose their fizz at higher temperatures because the loss of carbon dioxide in liquids is increased as temperature is raised.
This can be explained by the fact that when carbonated liquids are exposed to high temperatures, the solubility of gases in them is decreased.
High temperatures encourage gas to escape from the bottle thereby leaving soda flat.
The cooler the soda, the better the gas will dissolve in the fluid, which helps to retain the fizz in the drink.
The best place to store your carbonated drinks is in a cool and dry pantry or in the fridge.
You can chill and warm the soda over and over and as long as it remains sealed it shouldn't have any noticeable effect on taste, flavor, or carbonation once you do finally open it.
Now if you freeze it, it will likely explode.