With the talent glut at TE, WR, and even, arguably, RB, some people think Quinn Johnson will get cut this year, leaving us with only John Kuhn at FB. It seems possible, but I don't think it will happen, for the simple reason that being only one deep at a position--even a relatively minor position like FB--would cause the coach to throw out part of the playbook if Kuhn gets hurt.
While it is true that the TEs often line up in the backfield, I don't think this makes them viable FB substitutes. A true FB is built low to the ground, and when he gets up a head of steam he can hammer defenders at the line of scrimmage more effectively than a taller TE. This ability serves the team well in goal line and short yardage situations. So I think Quinn will stick, even though he is not an especially good player and does not appear to have improved much since his rookie year. The past two years, Ted has kept three FBs. This implies that the position is important to the team. Going from three FBs to one would be a drastic move, and in my opinion, an unlikely one.