Xilinx's official DisplayPort IP (seems to be from 3rd party) support HBR2(5.4Gbps) on 7-series and HBR3(8.1Gbps) only on UltraScale.
But GTX tranceivers on Kintex-7 already support 12.5Gbps, is there any physical reason (like physical signal formats) that HBR3 can't be supported by GTX tranceivers? If there is no such reason, then a more advanced (i.e. more parallelization with more resources) IP could get HBR3 on Kintex-7.
There is also the future DP2.0 which supports 10Gbps/13.5Gbps/20Gbps, it is possible to get 10Gbps on Kintex-7 and 13.5Gbps on Kintex UltraScale's GTH tranceivers if there is no physical reasons.
Note: only -2 devices are considered.