I am concerned Ireland will not be ready for what happens in Murrayfield (possibly with eyes on harder games to come) and if we lose there we will implode and probably get beaten by at least Wales and England also. Win in Scotland and without counting too many chickens I think our game in Cardiff becomes critical. Wales have often been the undoing of Irish championship hopes (and several English hopes too iirc). But as you say Sexton is playing like he has glass legs at the moment and we can't hope to win a championship if he isn't playing. Ditto Conor Murray. Not a poor injury record like Sexton's but the two half backs are the main if not only positions where our back up players are miles short of our first choices.

If it comes down to both Ireland and England going for the Grand Slam in Dublin on March 18, I think home advantage will favour us.

I would be more concerned about England's front row injuries than missing Billy V at No. 8. Nathan White is a very able replacement.