I would be really surprised if we don't draft a safety at some point in the draft this year. At the end of the day, both Harris and Martin are not under contract after next season and Reavo, Butler and Owens are not starting caliber players.
The safe play would be taking a safety at #71. I did an analysis recently and when you combine it with the depth of this safety class, you have a really good chance of finding a Day 1 starter. Furthermore, while the modern safety is expected to do a bit of everything, it is generally easier to find a guy who can play post safety well the earlier you pick.
Now, given the depth of this safety class, I think we will see future starters come out of rounds 5-7. Happens every year anyway and some of these guys really come up in a big way (Curl, Hufanga and Lake as examples). Obviously, hit rate is going to be meaningfully lower and the guy you take is probably not going to be a defensive contributor in year 1
If it were me, given Armstrong expires after next season, if a good EDGE prospect were to fall to #71 (Moore, Jacas, Lawrence, etc) and I thought he'd be a day 1 contributor as a rotational guy, I'm taking that guy given the way EDGE salaries have exploded this season and taking my chances on safety later in the draft. If that guy is not there, I'm probably defaulting to a safety at #71