Depends when he lands. If Renly is dead, Stannis is believed defeated and confined to the North, then yes there could well be a Targaryen restoration movement boiling out of the south that rolls up a disunited opposition
That seems like the current plan with Aegon and the Golden Company.
It’s also why I’ve never thought Tyrion’s plan, which Aegon seems to be following, was all that bad.
Well, Tyrion’s plan means Aegon doesn’t marry Dany and get a dragon…