Student or Learner
I will be able to speak French at the end of this course. (I feel less confident)
I can speak French at the end of this course. (I have confidence & the future is based on the current circumstances & there is a great possibility that I can speak French later, so can I use "can" instead of "will be able to"?)
The answer is still no.
Can is a defective verb;
(Wikipedia)In linguistics, a defective verb is a verb with an incomplete conjugation. Defective verbs cannot be conjugated in certain tenses, aspects, or moods.
It has no infinitive and is only used in the present tense.