"...But if you always use 'ain't' instead of the more “proper” contractions you’re sure to be branded as uneducated"
1- What does you're sure to mean?
2- Is it one of the examples of sentences that carry futurity in the present tense?
You are sure to ... = It is certain that you will ...
It is the infinitive, rather than the present tense that refers to future happening, as it so often does -
I hope/want/expect/am eager/etc to see you next week.
Like the 'being sure', the 'hoping, wanting expecting, being eager' denote present feelings about a future 'seeing'.
Note that in I will see you and I am going to see you, the underlined forms are present tense forms. As we have no future tense as such in English, futurity can only be expressed with present tense (and occasionally past tense) forms.