I was thinking lightheartedly, and a little more in the abstract.
However, I do think that with the passing of time, as the concept of marriage becomes less important to many more of us, that there probably will be some very wealthy middle-aged couples who have no children and possibly no other disapproving family ties, who look upon divorce as a valid way of saving potentially, many hundreds of thousands of pounds. There is nothing to stop them then living together, and enjoying the same quality-of-life as before, but without the social constraints or benefits.
Do I think it’s likely to happen? No not particularly, although as you say there will be a minority who do decide to do it. More likely I think, it could appeal more to those couples who are probably already on the cusp of deciding to divorce anyway (possibly as a result of having to spend more time together during this Covid melodrama) and will look upon this potential financial saving as being a very valid reason, possibly the one that tips them over the edge, to do so.