This one is complicated.
If it goes our way it means no more taking your guns away before conviction.
If I’m understanding things correctly.
You might be understanding things correctly, but no, it doesn't have to happen that way.
Remember, SCOTUS isn't limited or burdened by anything here. They don't have to say that a large number of laws are constitutional or not. They can be very specific, and indeed many SCOTUS cases often end up that way.
SCOTUS could easily say, "TROs must be evaluated on an individual basis to determine constitutionality, and this ruling only applies to the TRO before us today". There are piles and piles of SCOTUS decisions that are of exactly this flavor.
and then the Rahimi decision has no effect outside of Rahimi. I don't expect this to happen, but it easily could. Often you see such hyper-specific decisions when SCOTUS can't agree on the broad strokes of a decision effecting numerous laws, so they kick the can down the road and make a specific ruling for just the one case in front of them. Again, could happen, but we can afford to lose wishy-washy Roberts and still win 5-4, so it's less likely getting votes will be a problem.
As for the claims by the anti-2A crowd that founding-era racist laws prohibiting blacks/slaves from gun ownership somehow demonstrates that people the government doesn't like can be banned from possessing arms -- that claim is total BS. If SCOTUS is going to say TROs are due process or not that's one thing, but I'll bet money SCOTUS is not going to allow any tie-in to those racist laws. Similarly, founding-era religious laws against certain religions won't get any love, and I wouldn't be surprised if they get smacked down by specific mention in this decision.
There are other founding-era laws disarming people thought to be dangerous/disloyal, so there is a legit request here for SCOTUS to clarify the situation, and I personally think that's why SCOTUS took this case. Yes, there's a non-zero risk that SCOTUS screws the pooch. Lord knows we've won so much lately we're due for a loss, but I'm hopeful because this SCOTUS has generally done a good job.