In theory there should be a trade off when offering such a solution. Companies are more likely to trust you, and use your product if they can be sure there is a fallback plan (open source) upon your product being shuttered. Yes, you may lose some potential fallback plans for your company if it is being bought for its technology, but hopefully the number of additional adopters who would trust you early on in your company's life would compensate for this.

I'm not saying there is a moral obligation to do so, merely that it might be a good decision for both sides. See, for example, how open source is increasingly becoming a requirement for infrastructure products that companies come to depend on. This may be a good middle ground. Personally think open sourcing from the start is a better choice.