The acutal “exchange rate” of tokens to arena coins for the upper half of all ranks (all ranks getting 5 or 6 arena coins per PvP win without premium account) is 0.73333… tokens = 1 arena coin.
Any player playing the game on a pc while not getting any offers to watch ads to get the premium rewards after a pvp battle has to buy a premium account to get the additional 50% bonus on arena coins.
5 * 0.5 = 2.5 = 3 arena coins per win
6 * 0.5 = 3 arena coins per win
=> 5 wins a day * 3 arena coins / win = 15 arena coins a day
Optimal use of premium account for that:
8-hours-premium-account for 22 tokens used for 2 days (like purchased 4 hours before daily requests and PvP rewards reset and then getting 5 wins before daily reset and 4 wins after daily reset).
= 22 tokens for 2 days = 11 tokens a day
So 11 tokens a day would ideally be turned into 15 arena coins a day.
= 11 tokens / 15 arena coins
= 0,73333 tokens / arena coin
Therefore your prediction could indeed be true.
TS might make the costs for a premium box around 100 arena coins.
The reason I set it at 50 arena coins is that a player has to play the game in addition to paying the tokens for the premium account as well as that the premium account.
Furthermore getting the “ideal” timing for the premium account is almost impossible cause players have to work, too, and hence would mostly not be able to play shortly before and shortly after the daily reset.
Which means that the actual need of tokens would be more likely 22 tokens a day on work days (Mon-Fri) and 22 tokens for the weekend (Saturday + Sunday together) = 132 tokens in total.
= 132 tokens / (7 * 15 arena coins) = 132 tokens / 105 arena coins
= ca. 1.26 tokens / arena coin