Possibilities and Probabilities
Uncertainty is part of human life. Talking about possibilities and probabilities lies in the nature of life in general and human nature in particular. Nothing can be guaranteed. It is important to keep in mind that reliability tends to be measured in "the number of 9s" – in other words 99.9 percent because nothing is 100 percent reliable. Who can then guarantee anything 100 percent? There is always a scenario where something can get lost, change or stop to exist altogether. You can of course try to increase the degree of reliability and reduce the likelihood of failure. This will probably add another 9 to the reliability rating but cannot make it 100 percent bullet proof. Uncertainty can be expressed in English in a variety of ways depending upon the degree of likelihood. Will + words of uncertainty or its substitute may and might are used for showing possibilities.. Note the position of will in the following:

Will follows words of likelihood:
Maybe, I’ll phone you this evening.
Perhaps I’ll phone you this evening
I think I‘ll phone you this evening.

Will comes before words of likelihood:
I’ll possibly phone you this evening.
I’ll probably phone you this evening
When put into negative the word order changes:
I possibly won’t come to the party.
I probably won’t come to the party.