> The current chain is effectively single threaded.

This is not true, since xthin/compactblocks have been introduced we
completely removed this bottle-neck.
The transactions will be validated continuously, in parallel and not just
when a block is found.

If I understood correctly, OP was not talking about the process inside a node being single threaded, but instead that the whole bitcoin distributed system behaves as single threaded computation. OP seems to be describing a system closer to what IOTA uses, by distributing among the miners the task of validating the transactions. Although, without more specific details, it is hard to judge the benefits.