It is really not that hard to get the major manufacturers to look at a new game concept. The main thing is that you must file for a patent before approaching them. If you haven't filed for a patent, most will not even speak with you about it because they want to protect both yours and their interests.
On the other hand, casinos aren't buying new video poker games because there isn't enough profit. The casinos realize that 99% of gamblers will play whatever games they offer and the video slots they are buying have a 10%-14% hold. If you can come up with a 99% video poker game you will have to get ten times as much handle as the video slots to even have a chance.