I'm pretty sure the entire Findlay line will have to go extinct before you even have a shot at becoming Colonel.
But as Lieutenant-colonel to Cunaris, who can't walk or ride, you basically field-command the entire regiment anyways, while Cunaris deals with the soul-rending paperwork.
Although that'll probably change if or when Renard takes over. But even then, (speculation ahoy!) if you have a good relationship with him you might even be able to command the regiment through him. You are after all his second in command, and he recognizes and respects your greater experience.