He'll come before supper if he comes at all

[Sitifan]

He’ll come before supper if he comes at all. (Michael Swan, Practical English Usage)
In the above sentence, does the phrase “at all” implies that he probably will not come?

[Torsten]

It means that if actually does come, he will come before supper. It also means that he might not come.

[Alan]

The use of ‘at all’ here strengthens the force of ‘if’ . In fact it would have the same sense of -’ if indeed he comes’.

[Oefie6Dei]

Yes, the author is not sure that he will come.