It has been mentioned many times, both in the past and more recently. It does start to get a little bit boring with it coming up all the time. However as mentioned in the many past threads about this, Jet2 probably wouldn't bother, they can expand on their own if they so wished, without the need to purchase a company and all the expense that goes with it... (changing terms & conditions, pay, rebranding, marketing, lease agreements etc etc)
In my opinion WW isn't really a threat to LS or vice versa. They both offer good competition at their airports, without having to put up fare fights like that of FR. So to me it would be pointless.