FontOptions is not a replacement for the Font Class. It’s another class that specifies certain options to be used for the font. As @chrhaase mentioned, it’s just the constructors that now require a FontOptions class to be passed. Also note that these two are equivalent:
titleLabel.setFont (FontOptions(16.0f, juce::Font::bold));
titleLabel.setFont (Font(FontOptions(16.0f, juce::Font::bold)));
because of “implicit conversions”. So what you have now is fine moving forwards in JUCE 8. See also: