I believe that he will start the season there, but when Hecht is back and able to play they will send him to Portland to play top line. That is if he doesn't keep up his preseason play, then I believe that he will be up for the year.
As of now he is in between Vanek and Pomenville, but I can't see them not putting Roy in there come the season opener.
He travelled with the team to Europe and will battle with Matt Ellis for the last roster-spot (i think Hecht will be out for at least a few more games). Since Ellis is a 4th liner, whenever a spot in the top-9 needs to be filled Luke should be the first option. Ruff could decide to move another 4th-liner up and insert Ellis into the line-up, but Adam had a decent pre-season so i think that is unlikely. He will at least get the two games in Europe and everything else decides after that, when we see how he has played and when there is clarity about Hecht.
He certainly isn't a lock for the #3 C spot, but he will most likely start the season there. I think he has a pretty good chance to stick around and play 60+ games due to injuries, even if he only plays 'okay'.