Actually bonds in rs3 may go up in price since they'll be going up from around $3.50 to $5.00.
If Jagex made bonds the same price in rs07 and forced it to stay there the price of gold would very likely be forced to decrease to accommodate the increased price in bonds.
So if 07 bonds are made 7m ea essentially 7m rs07gp would then be worth $5. This wouldn't hurt Jagex at all just big gold farmers which is likely one of their intentions in order to crack down on RWT(though it could be argued bonds made RWT legit with the only difference that Jagex is the main beneficiary and not some random 3rd party company). This leads me to believe the price may drop if Jagex does such a thing and why wouldn't they, it'd mean so much more money for them.