This appears to be already released, just not yet announced.
Jagex Account Guardian (or JAG) is an optional security feature that provides an enhanced level of security to help RuneScape players protect their account. Once enabled JAG limits in-game access for your account to specific devices, which have been authorised by you.
Devices can be added temporarily or permanently, as well as being removed at any time using your registered email account and some security questions.
With JAG enabled, unrecognised devices will be blocked from accessing RuneScape and will need to go through some security checks before access is granted, even if the current password is known.