Tubes on low- to mid- range civilian DE guns can burn out very quickly, and are in fact designed to do so long before you get damage to the more expensive parts of the gun - I've seen it happen in most of the cases (which are admittedly quite few in number despite how often I'm there) where I've seen someone using a bump stock at a range. In the most recent case I think the guy was on his 3rd mag and it ruptured. It was a M&P 15 Sport II, if I recall. Not a cheap no-name brand, but about as low-cost as you can get and missing all the upgrades in the version they market to cops. High-end ARs would fair better, I'd expect, but high-end ARs are again so rarely used for actual violence because they're usually only purchased by people shooting for a serious hobby in stable life situations. And honestly I feel the same people buying those probably feel bump stocks are tacky and gaudy like I do.
Even in the most liberal interpretation of the proposed law, I don't think any bump stock ban would become a semi-auto ban. I could see the vague language getting applied to after-market triggers, especially ones like Franklin Armory, but you've gotta have some added device for any of the proposals I've seen to even remotely apply.
<off-topic> This is non-sense. Typical semi-auto are wayyy over build. Unless mechanical wear or explicit tempering of the disconnector, there is no risk whatsoever to fire thousands of rounds with a bump stock. Actually, plastic/wood furniture are more likely to burn/melt before the mechanical parts will actually fail. As worst, you might bend a gas piston, but the rifle will otherwise be fine.
The underlying reasoning behind the push against the bump stock ban is that it was basically a semi-auto ban, as you can trivially with a bit of training bump fire any semi-auto without a bump stock from either the shoulder or the hip with a mere finger. </off-topi>