Is it likely that a company hold open a job position for 10 months until I transition?

NO

Listen all is not lost. I have seen company’s waite, you just need to inform them that the military will not allow your to separate earlier. Express your desire for the position and that you know you can contribute to the Companies future success etc. thank you for your service.

That should have been addressed with the company before you got far into the selection process. Your cover letter is a good place to cover that. If it is a small field, it could come back to bite you in the butt. HR professionals, within smaller metropolitan areas talk to each other.

All is not necessarily lost, at least in my day, about 15%-20% of new hires were either determined not to be good matches after a few months; or work for a few months, get a better offer then move on.

Your next best bet is to apply for early discharge.

If you are ETSing, you are "authorized" to leave early as long as you have actively applied for a job and have been accepted for it. Go to your Battalion S1 and inquire about an "Early Separation" due to a job waiting for you (this means DA 4187 request that will come from you through your unit to the BN CDR, etc), the most you might get would be 6 months out but that's still less than 10 and if you have told the employers about your situation, if they really need you then they'd wait or else they'd take the Joe next in line...