So are manufacturers of suppressors and distributors of suppressors going to sell them in Tennessee to in state residents without a tax stamp?
Yeah........No.
In theory, sure. But I doubt you'd get anyone with an FFL of any type to partake in it. Similar to the marijuana industry. Early on (and still to some extent) those willing to start businesses were subject to raids, inability to find a bank that would maintain accounts for them, etc. Would also depend on the Administration's position. Obama took a more lenient position on pot as his Presidency went on, so in theory DJT and Sessions could direct the ATF to not interfere with suppressor businesses in Tennessee/other decriminalized states and in theory the ATF would not interfere, and the locals would not interfere to comply with State law, and in theory Tennesseans could have their shushers. But unlike the pot industry, there isn't as much money in the suppressor industry, so I don't see anyone taking that giant leap forward.