The Lions were given an extra 24 hours to sell the final 2,000 tickets they had (tickets are still available, but they were returned by the Eagles). According to Tom Lewand, no outside help was required to sell the tickets, so fans were solely responsible for the sellout. (In the past the Lions have had the remaining thousand or so tickets bought by a company to achieve a sellout, but that was not the case in this instance.)
What this means is that for this week, there is no blackout. Going forward and looking at the home schedule, I'm not all that optimistic that there won't be blackouts, especially with the next home game being against the Rams, but for this week anyways, those of us in the local area can watch the Lions.