We've released MIUI 7 China ROM and Global ROM in the last couple of weeks. Now most of Xiaomi devices can upgrade to MIUI 7. Soon after the release of MIUI 7, we updated the MIUI patchrom tool, and released it last Thursday. (Find it here)
After the release of the Patchrom tool, MIUI China Forum Porting team members have worked very hard to bring MIUI 7 to 3rd party devices. Here's a collection of their works so far. Is your device listed? If not, you can make a request here.
Please note that this is MIUI 7 China ROM. And ported ROMs are not tested by MIUI officially, there might be risks flashing the ROM. Please think twice before you start the procedure. For any bugs found, please report here.