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The spammer increasing their fees just causes legitimate transaction fees to increase since wallets use dynamic fee calculators, this prices the spammer out of the blocks since transaction fees are relatively small for the legitimate users but large for the spammer(since they are trying to buy a lot of block space). Without a cap fees would likely be too low to price the spammer out of the blocks.
The spammer increasing their fees just causes legitimate transaction fees to increase since wallets use dynamic fee calculators, this prices the spammer out of the blocks since transaction fees are relatively small for the legitimate users but large for the spammer(since they are trying to buy a lot of block space). Without a cap fees would likely be too low to price the spammer out of the blocks.
The point of the spam is not to buy blockspace since there is way too much spam for that, or even compete with the ham but only to spam the nodes. Fee filters are not a defense since the spammer sets her fees above the filter but below the ham.
Ok, So this is an attack targeted at nodes. Why would someone go through all the trouble to do that? Can this be a strategy to force people to accept SegWit or to make them realize that it is needed? The other possibility is that this is a external attack from a competitor, to take the network down.
What would be your opinion on the motive for this attack?
First We need to be sure If It's an attack on the bitcoin Network. As You say, I don't see any reason why someone will go through or the stress for flood the blockchain with Unconfirmed Transactions.
If It's an attack to made people embrace Segwit and Unconfirmed Transaction become more consistent, We may have to adopt Segwit.
Yeah I've been waiting over 8 hours. I hope it somehow confirms soon 
Over 8 hours? I'm extremely worried over My transactions that have been stucked for 3 hours now. Maybe we just need to wait a little longer
