Well, you already have some form of French gunboat-policy in Algeria by 1827 and 1829, mostly based on diplomatic incident and unwillingness of French government to pay the depts contracted by the Republic (weath supply).
Even if the 1830's expedition was partially driven by inner policies, expeditions planning was already made since some time by then. It's only a matter of time before it was enacted : if not 1830, then 1831.
That said, you could end with protectorates over coastal Algeria, at least for a time, Tunisia-style, rather than direct annexation.