Cap number is a % of overall revenue that the game grosses (around 25% off the top of my head), which includes TV rights, sponsorships, licensing (merchandise) and tickets (some others as well, but they're the main ones).
The annual TV rights cash is about an 80% increase on the current TV deal. It is also the main revenue stream out of all the categories I listed above. If all the revenue categories increased at the same rate as the TV deal, the cap would increase by around that 80%. It's unlikely the other streams would increase at the same rate (ticketing for example won't nearly double in price), but conservatively I'd say the cap will increase at least 50% shortly into the new TV deal (afl may not jump the cap immediately, and may increase it over the period of a couple of years to get to the overall increase in time).
Long winded way of saying the cap will go up a shedload. Unless boyd's deal has a clause granting him an automatic increase in line with the cap increase (which it may), he won't be the highest paid player at the club by the end of his deal.