Let’s consider the following sentence. Here, the writer believes that the government is highly likely to increase taxes (we know this from the use of 1st conditional). The use of will in the main clause tells us that the writer is certain that the effect of raising taxes will be that companies move their business overseas. We can talk about different levels of certainty of the effect by using different modal verbs. The use of will probably in the main clause tells us that the writer believes it is highly probable that the effect of raising taxes will be that companies move their business overseas. Will most likely can also be used instead of will probably to express the same level of certainty. In this clause the use of might tells us that the writer believes that companies moving their business overseas is only a possible effect of raising taxes. Could and May can also be used instead of might. Remember that the modal verbs used here only change the certainty of the effect. The sentence is still first conditional which means that regardless of the effect, the cause –the government introducing higher taxes – is still a highly likely situation.