Do we really expect all of these companies to be working on trading platforms? Mining? Video Hosting? Etc...
In the first place, since there is no gambling exist, then yes.
Companies will work on other subjects and services just like as we see it today.
Do we really intend to be good citizens if this were the fact on our life?
There are surely other forms of entertainment that might exist if gambling doesn't exist.
Honestly, I'm having a hard time putting the situation to
"what if" if we have to talk about gambling doesn't really exist in general. I mean, yes it's impossible since even back where any physical forms of money don't exist yet, some of the activities are associated with gambling already. For example, a simple barter trade between tribe to tribe, country to country, region to region, island to island etc. - these trades happened because other parties want a good product in return and that's already a gamble since it's a win-win situation if a certain party will really get a good product.
My answer above is based on a certain country or location that gambling is strictly prohibited and illegal. I hope I get the picture of this thread.