Loughran doesn’t have the power to command respect from Golovkin, but he definitely had the boxing ability. Who wins?
Loughran was a boxer-mover type and Golovkin never has had any problems in closing these guys down. GGG's footwork is the business. That's what makes me think that he could make his power and accuracy count. Now granted I haven't watched Loughran in ages so making a fair stylistic evaluation is kinda iffy right now. But iirc Tommy was good at creating space, had excellent timing and would often potshot chasing guys and then move off again before they could fire back. Golovkin is great at making a ring small and at timing too, particularly with his jab which he uses to disrupt the other guy's rythmn and to hit first. I feel that if Golovkin forces Loughran to fight, then his physicality and power tip the equation towards him.
I lean towards Loughran on points, and it woudl be more exciting that you might think. Despite his lack of power. Loughran was prepared to mix it up with punchers, in order to steal rounds.