There's lots to be fixed across the OHL/CHL to increase attendance but unfortunately they won't be willing to fix things.
The product has become watered down and over priced and there base of support supports one style of game while the fans they are looking to attract will never see the product they want because of how watered down it has become.
The changes to trading draft picks is a start, but they should really reduce it to 3 years instead of 4.
After that?
Contraction. Get the league down to 16 teams. Will help to centralize the high end talent when there are fewer markets.
Balance the schedule, everyone would play each other 4 times (with a 16 team league that would cut the number of games to 60 for those who push the education perspective it becomes more attractive). The league could continue to be split into two conferences or simply eliminate the conferences and rank everyone 1 - 16 for playoffs with the top 8 making the playoffs. This should provide better match ups in the playoffs with a better likelihood that the best teams are moving onto the championships.
Institute a draft lottery similar to the NHL to minimize the chance a team will look to tank. When last place no longer guarantees you the first pick everyone has more to play for.
Cut the draft from 15 rounds to 10. There are a lot of players who will never have a chance to play in the league that are drafted simply to fill 15 rounds. Keep the focus on the top players, on fewer teams and the level of play will pic up significantly. There is the argument some will have about late round gems, sign them as FAs. That same argument can also be applied to the NHL which only has 7 rounds. How many rounds do you increase the draft by until you no longer have late round gems to worry about? Teams already sign undrafted FAs so cutting the draft won't make much difference.
Eliminate the U18 draft. Nice experiment but doesn't appear to be working or adding much to OHL teams. I know the reasoning is to keep kids playing midget level hockey but with JR. A, B, C, Tier 2 etc they have options if they have the talent.
Cut the import draft to a single round but increase the number of imports a team can carry to 3. This allows even more high end talent into the league and when you can increase the level of talent you increase your ability to keep attracting even more high end talent. Keeps the "warm bodies" to a minimum within the league.
Eliminate the import tag from OA imports. While you still won't see many OA imports if a player has come over to play as a 17 and the opportunity to play an OA year comes along the player/team should not be punished for keeping the best players possible. Keep the number of OAs the same but an OA import would not count as an import player. The only stipulation is they would have had to play at least one full season in the league to qualify.
Start targeting players at 14. Obviously not to draft but the CHL as a whole needs to come together and put their product/development model out there to the kids as soon as possible in a way that makes dense. Development camps across the US etc for top level potential prospects with league follow up for 14/15 year olds before their draft year that involves all teams from the CHL and its various leagues. Make sure it doesn't interfere with their NCAA eligibility so that you can attract them to it but when you can provide events that put the highest level of kids together in their respective age groups and the kids can see how that level of play improves their development opportunities and the potential to help their pro aspirations you increase interest in the league(s).
Increase the talent and you can increase the level of competition, attractiveness to players and attendance. Ticket prices are an issue right now but the bigger issue is not simply the price of tickets but the quality of product available for the price of tickets. If you have a good product that people want to see ticket prices become less of an issue.
Why do so many players come out of the GTA? The talent is centralized amongst a few teams and if players want to improve their chances of making it beyond minor midget they find ways to play there. The OHL/CHL needs to build off of that model.