An increase of TPS is already being discussed by core-devs, and they are trying to find the optimal way to implement it.

With a very large percentage of BTC txs being dust, they have plenty of time to figure it out.

What we don't have the luxury to do, is to start rogue forks that create friction in the dev community. But then again, what doesn't kill you makes you stronger.

As for spam, fees and block sizes: Altcoin Monero has a dynamic sized block. Let's say that, dynamically, the size can enlarge significantly. When it was spam-attacked last year (hint: the bloat created by anonymous coins is multiple size that of bitcoin), do you think people were like "oh, it's ok we have big blocks and we are ok"? No. They had to quickly implement high fees to stop the attack as it would bloat it to unusable levels. It was the fees that stopped the attack, not the self-adapting increasing blocksize.

LTC also used a patch, in the past, to prevent some spam techniques that were used against it. BTC might need to integrate it too.