Yes, you should bring more money into the game in order to balance out the increased median salaries and restore value in training.
Yes, you should do part of it via merchandising. The current idea seems legit but the percentage needs to be higher imho. Around 20-25% at least. You could think about binding it to the next paid player if the aim is to have superstars dispersed more evenly. The higher the difference - the bigger the bonus.
And yes - you probably should bring a bit more money into the game via the TV contract as well. But definitely you should also increase the salary floors (%) in all divisions. This will achieve two goals at the same time:
1) Will make tanking much less efficient. Competitive teams won't feel it at all.
2) Will virtually give a bit more money to teams in lower divisions (the salary floor is a percentage of TV money - the higher the league level, the bigger the %)
BBB: 2 (S37 S38); Top tier: 7 (S35 S36 S37 S38 S39 S41 S63); Cup: 9 (S25 S35 S36 S37 S38 S39 S40 S41 S61)