I'm not sure it much matters. Exchange consolidation has been going on for much of the past decade, and I can recollect going to a conference about six years ago where the contention was when, not if, TSX would buy MX. The next question was when Nasdaq would make a bid for both. Of course, Nasdaq's market share has been eroded by ECNs or ATS's — be careful what you wish for with electronic trading — and so has NYSE's, which is why it bought Arca, an ECN.

The real question, at least for regulators, is do we have a retail-friendly stock market? The institutional investors can do upstairs trading with the bank brokers, or submit their bids through dark pools; we no longer have a single marketplace. As a result, it is trading rules, rather than ownership, that matter on the retail side

On the other side of that is how many financial service industry jobs would be lost with a merger. Not many, I suspect, except in the executive ranks. The heightened speed of trading will require ever more IT people, and the increasing volume of trading requires ever more brokerage employees.

In the end, exchanges are not going to make it through trading fees (there's too much competition) or listing fees (depending on the friendliness of the jurisdiction) but on trade info — in other words, as data vendors. That shift was apparent in the mid-2000s.

So I'm not sure there's all that much to worry about.