The acquiring company basically cranks up their fees to the acquired customer base to weed out anyone that a. doesn't have deep pockets and b. has an alternative. The customers they are left with are then stuck with you and you can continue to ratchet up prices while cutting costs for years. of course this requires that the software in use is hard to replace, or in the parlance, has a big moat. if you get it right you can make billions with this strategy. after all, an unhappy customer makes more money than a happy prospect.

conversely, any start-up that can bridge the moat is guaranteed a thrilling ride.

My guess is ruthlessly cut costs and gradually degrade remaining customer good will until it's a dessicated corpse.