Your argument assumes that Trump has both the knowledge to determine what policies would result in positive net change in the heartland and the power to get then in place. Even with the same party in control of Congress, President's don't always get what they want, and moreover politicians are quite often wrong in their assessment of what policies will produce the results they prefer.
And that’s even before considering that politicians often have interests in policy other than reelection, and reelection is often secondary and instrumental to those signs rather than primary over them.
They don't have to be right in the assessment, they just have to make it look like they tried real hard and any failures are not their fault.
For example steel tariffs are meant to benefit Trump voters (at the expense of the rest of the country). If it turns out they don't actually benefit Trump voters, he still gets points for being the only one willing to try.
It's similar to the security theater that the government uses to fight terrorism. It doesn't matter if it doesn't work, because being seen trying and failing gives more points than not doing anything.
They do to support the prediction that “it doesn't take a genius to see that the heartland will see improving conditions going forward”, based on Trump's political need for heartland votes.
I agree with you that things don't actually have to get better for Trump to get votes if he can sell it as something else blocking his efforts, but that just further undermines the claim I was responding to.
> our argument assumes that Trump has both the knowledge to determine what policies would result in positive net change in the heartland and the power to get then in place.
Also, it assumes that Trump desires a second term or actually believes what he says. As evidenced by his recent schizophrenic behavior on gun control, the biggest threat to "Trumpism" is Trump.
And that’s even before considering that politicians often have interests in policy other than reelection, and reelection is often secondary and instrumental to those signs rather than primary over them.