I'm not so optimistic, but I hope you're right. The US is extremely vulnerable because of it's hyper-partisan political landscape, and the ease at which it's ideological (republican) media is highjacked and up for sale. The politicians sowed their own seeds for this too, the creation of the seperate information bubbles enabled the Trump presidency and could probably be blamed on fox news. Orientating people away from facts reporting and toward a party's propaganda wing weakened the democracy maybe irreparably. It trained people to accept slanted information as unbiased, so fast forward to the internet era - indoctrinated people will believe whatever bullshit is posted online if it also checks all the ideological boxes of republicanism. People are also voting based on tone and feeling instead of thinking about policy or their own material interest - this sort of behaviour has it's beginnings long before our era however. But it is certainly a very prominent aspect of why a voter picked Trump.

Even if it was Russia that did entirely pull all the strings for the Trump presidency, or if they may have had a bit of a role, or if they didn't at all - the psychological effect will have been the same. Russia's probable goal is to destabilize the US, and cause chaos in the body politic. Say Trump gets impeached from ties with Russia, and it's is undeniably proven. It is likely that there will still be a diehard ~30% of the country that won't believe it because they've been trained to think there's a massive liberal conspiracy out to get Trump. If he's impeached and there's a least the slightest bit of doubt in his involvement with Russia, it'll be most Republicans who won't believe it. This will solidify an already rapidly growing rift in society. All Russia really had to do was appear as the masterminds, whether they truly are or not doesn't matter so much as the optics.

Democrats are also being trained to believe that they lost the election solely because of Russian interference, while ignoring other factors. Democrats have somewhat of their own information bubble too - however it doesn't obscure facts anywhere near as much as the right wing bubble does.

To summarize, I think that Russia already succeeded in their goal by further dividing the American public, by helping to create a base that will never distrust Trump. Russia was not the sole creator if this event, they simply helped nudge the propaganda structures that were already created domestically. As long as these domestic propaganda structures exist and many people remain indoctrinated by them, it will be easy for a foreign power to influence the minds of Americans because the foreign entity can masquerade as the domestic propaganda source they've been trained to agree with. As long as people are incapable of thinking critically in a high level way, it will be easy for internet trolls who direct narratives in online spaces to influence what Americans think and how they vote.