I think TK hit the nail on the head. Old players will diminish over time. Honestly, counterintuitively speaking, it might work the opposite way. If you have a lot more new players and a more active community, you may get a lot of old players back. Remember, not all players coming back have to be top tier. Naturally, there will always be a high population of average players. Hence the word average, ha.
TK that is a lot of money to spend. If you are going to cut corners, imo, spend less on the top tier players. They can play for w/e money we already provide and many play for the competition. We don't get many top tier players coming back for tournaments anyways. That was only for Burnts and that is long gone.
New players don't have enough new players to play with, so yes, there needs to be a higher population of them at once, I agree. 50 is quite an aggressive and admiral goal but even 15 would be suffice.
For the tournament you could even put, people with 1-3 months of ever playing the game qualify only, games work just as well if not better. (Tora IP check), this way, if they are interested enough, they will play for that long and by that time they either like they game or they don't. Random hasted thought. No pun intended.