It seems Comcast & Disney view their theme parks in a different manner, business wise.
*If Comcast wins the bid I don't think it will have a negative effect on their theme park plans. Comcast seems to view their parks as a profit generator, and they seem to want to increase the size of that particular business segment in order to produce even more high percentages of profit.
* Disney theme parks produce very good profits on a consistent basis. But Disney seems to place more value in taking revenue out then in long term investments in the parks. These latest expansions have been mostly done as an answer, and fear of, Comcast taking market share away. If there was no Comcast in the equation, most of these expansions would have never taken place. With theme parks almost an afterthought in the Disney corporate structure, I could see a scenario where park development is slowed if they purchase Fox, and they (Disney) concentrate investment in other areas.