8MB could last for a few years before needing to worry about it again.
8MB will "work" until someone wants to enforce a change again and pays for the "stress test".
LTC fixed the spam issue in 2015.
There is nothing stopping BTC from using the same type of fix.
https://cointelegraph.com/news/litecoin-shows-there-is-a-simple-fix-for-spam-attacks-on-bitcoinCT: Can you explain why Litecoin is immune to the spam attack?
CL: The fix implemented in Litecoin is just to charge the sender a fee for each tiny output he creates. For example, in this specific attack, the sender is charged one fee for sending to 34 tiny outputs of 0.00001 BTC. With the fix, that fee would be 34 times as much. So it would cost the attacker a lot more to perform the spam attack. The concept is fairly simple: the sender should pay for each tiny output he/she creates.
with small fee attacks. right now they are doing random sizes with random amounts and high fees virtually undetectable by code. but they have been found.