Recently Ai finally added hotkeys slots for text formatting (following this request: http://illustrator.uservoice.com/forums/333657/suggestions/33679330) — for bold, Underline, Italics.

We need more.
Even though Strikethrough (as well as Underline) in Ai is very basic and does not allow customization (here is a request about both: http://illustrator.uservoice.com/forums/333657/suggestions/48103976), we need at least an empty hotkey slot for it. Most apps support Cmd/Ctrl+Shift+X for this, so I suggest the same combination.