Neither of these scenarios really make sense to me.
Canon does not need A4 engines, they make all of HP's. So why acquire Lexmark? If Ricoh could afford it (both money and integration capacity-wise) that would make more sense.
Canon is a proud and rich company and is not going to be acquired by HP or anyone else soon. It made over $30b last year too.
HP sees itself as a solutions and service provider, not a manufacturer, it would much rather Canon take care of the manufacturing and the headaches that go with that - HP would not want to buy its supplier.