Looks like the midget in the speaker's chair would rather retire to the shire than risk losing his seat in the election
The speaker's seat generally goes uncontested, at least by the major parties. I guess the Brexit party would contest it, but there's no way Bercow would have lost his seat if he went for reelection
Also, fun fact: Buckingham voted remain. Not by a particularly large margin (48% Leave), but voted remain nontheless.
The Tories announced that they would challenge him for breaking his neutrality. His seat is a remain marginal but it is ancestrally Tory
Even so, it's easy to see Bercow holding on to the seat running as speaker. It's an ancestrally Tory seat, but they would lose a bit of their vote to the Brexit party, while the opposition would be unified (no remain party would contest it; not Labour, not the LDs, not the Greens).
It would be close, but I imagine Bercow wins with a percentage in the 40s. Of course, with Bercow out it's now safe Tory.