We won't play tactics that require an attacking fullback (we needed those last year). If we keep playing wingers like Krasic (or Seba style wingers) then it will be very good to have solid defenders. Actually, no matter what we play, we will still desperately need a RB and a LB that defend really well.
I'm all for the rumors linking us with Lazio's fullbacks. But we will need a kickass LW in that case, because Radu hardly ever contributes in attack, unlike Licht who has the strength to run up and down all the time.
Even if neither of Radu/Lichtsteiner seems like an attractive option, they will be an excellent addition, you can trust me on that. It will be an especially successful transfer if there is truth in the rumors and Martinez or Amauri are included in a potential deal like that one. We will not only improve the defense a lot but we will get rid of players we don't need and pay less for wages in the process, leaving us more money for a great LW we will desperately need.