Seems like the story usually goes like All Quiet on the Western Front until one, or two, companies make the first move then it's like the dam bursts and all that pent up M&A money (sitting on the "shelf"), pressure and fervor is released all at once.
Companies are also subject to FOMO when M&A, and consolidation of industries start snowballing
In other words, for me, it's just a matter of time, but when? Who knows.