By the time Henry IV came to the throne, it was far too late for a French monarch to make the kingdom Protestant. It became much harder for monarchs to change the people's denomination once people identified as Catholic as opposed to Protestant, or Lutheran as opposed to Calvinist. Bourbons staying Protestant would only mean more religious toleration, civil war, or both.
French kings during the relevant time period also had ambitions in Italy, which would be much more difficult to pursue if they were Protestant. It is entirely plausible, however, that those claims to Naples and Milan might not have been inherited by the French King.
French kings during the relevant time period also had ambitions in Italy, which would be much more difficult to pursue if they were Protestant. It is entirely plausible, however, that those claims to Naples and Milan might not have been inherited by the French King.