The modified hash only applies to signature operations initiated from witness data, so signature operations from the base block will continue to require lower limits.
The way it is worded makes it sound fantastic...
However, I couldnt find info about the the witness data immunities from the attacks. Are you saying that signature attacks are not possible inside the witness data?
Clearly if signatures are moved from location A to location B, then saying signature attacks are not possible in location A. OK, that is good. but what about location B?
Are sigs in the witness data immune from malicious tx via lots of sigs? It is strange this isnt specifically addressed. Maybe its just me and my low reading comprehension. But all the text on that segwit marketing page seems quite one sided and of the form:
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things are removed from the base blocks so now there are no problems with the base block, without addressing if the problems that used to be in the base block are actually solved, or just moved into the witness data.
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We could easily say SPV solves all signature attack problems. Just make it so your node doesnt do much at all and it avoids all these pesky problems, but the important issue to many people is what is the effect on full nodes. And by full, I mean a node that doesnt prune, relays, validates signatures and enables other nodes to do the bootstrapping.
Without that, doesnt bitcoin security model change to PoS level? I know how much you hate PoS
James