You'll get more than 50 deaths.

You get 1 train every 5 levels. You can also trade 10 practices for a train. You can use these to increase your con when it decreases.

You'll have way over 100 deaths before you con die if you use your trains for con. I pulled some PBF (Premium battle field) data for all of the con-loss half drows and it's usually been between 60 and 80 deaths before con death.

It all depends on how many trains you want to spend for con/hp etc.