Are all 5* characters going to be able to be awakened at some point or just certain ones?

Certain characters can only be awakened to 6*.You can check if a character can be awakened to 6* by checking the stars.If a star is missing,you can awaken the character.

Thank you for your post. bwf182 answer to your question.
Currently just certain characters can awaken to 6*. These characters get announced so we know which ones they will be. Currently there has not been anything said about current 5*'s being able to awaken to 6* but that doesn't mean that won't change in the future.