It has been done. The delay functionality is working. Works on Vista and 7 (and probably 8, 8.1 as well).
This Snipping Tool is from Windows 10 1507 (the RTM release). The SHA-256 hash of the original SnippingTool.EXE is "fccf231e0e4437baba86f64752e13562c9a2aa2d699a8dae7fafc85b48da4aa8"
Porting requires 2 hex edits: one to change the NT version from 10.0 to 6.0 in order to trick Windows into running it, and the second to bypass some licensing/permission check that Microsoft put in.
Dunno if it's fine to distribute the .EXE here (probably not), hence why I only include instructions.
These instructions ONLY WORK FOR x64 Snipping Tool. If there is a big demand I can also work out how to do it for the 32-bit Snipping Tool as well.
1. Obtain Windows 10 1507 RTM x64 ISO, open with 7-Zip, then open sources\install.wim with 7-zip
2. Go to Windows\system32 and drag SnippingTool.exe to desktop (or some other location)
3. Next to SnippingTool.exe, make a folder called "en-US" (or whatever your language code)
4. From your 7-zip window, go to Windows\system32\en-US (or whatever your language code) and drag SnippingTool.exe.mui into the "en-US" folder you made in step 3
5. Open SnippingTool.exe in HxD or some other hex editor
6. At offset 0x120, change "0A 00 00 00 0A 00 00 00 0A 00 00 00" to "06 00 00 00 06 00 00 00 06 00 00 00"
7. At offset 0x1D19C, change "40 55 41 54 41 55" to "B8 01 00 00 00 C3"
8. At offset 0xF6B0, change "B8 FA 00 00 00" to "B8 2C 01 00 00"
9. Save file and exit hex editor
At this point, you can simply open the edited SnippingTool.exe and get the Windows 10 snipping tool as pictured. You may also replace the Windows Vista/7 stock snipping tool with this one if you desire.
For reference, the SHA-256 hash of the modified SnippingTool.exe is supposed to be "c60898fb4ea6984aaee1f2d3c9b73560bf0aaff64b9855e3d58e9855f3836433"
"It runs but only displays an error box with no text!"
This is caused by incorrect MUI file, or incorrect placement of the MUI file.
As in picture, en-US folder should be next to SnippingTool.exe, and SnippingTool.exe.mui should be inside that folder. And keep in mind, everywhere I say "en-US", this means the language code used by your system. For example, ja-JP or fr-FR for Japanese and French respectively.
Edit: Add bug fix for ghost menu entries in certain circumstances (this bug happens in win10 as well)