From people oposed to SegWit I have heard about the argument, that after SegWit activation, nodes may chose to drop/prune all Witnesses. From my understanding, this may not be much different from nodes who are already only storing a pruned version of the blockchain. And a node using the ruleset from SegWit would not accept a block without the witnesses, only the backwards compatible nodes that do not follow the ruleset from Segwit would?
My question is what the default behaviour of a core node is, when it receives block up to X, and the blocks thereafter are only header-files with the actual block data pruned.
In other words: what happens if my node is somehow kept away from the true/whole bitcoin network, so that my node only receives pruned blocks which cannot be verified. Would my node only accept the blocks up to the one which was a block with complete data and drop the rest until complete data is received for those? What if my node is a mining node?