Since patch 1.1, are Hydras more viable against Terran?

Solution 1:

I think Idra said it best:

The tank's damage was also changed from 50 to 35+15 vs armored, but this is essentially irrelevant in ZvT, they will now kill hydras in 3 shots instead of 2, but hydras are not usable vs terran because of their poor mobility and ridiculously low hp.

What he is getting at is: although they are now better against Siege tanks, the fundamental problems that exist with Hydras have not changed. If you didn't feel you were able to use them as the basis for your army before, then you shouldn't now.

On the other hand, if you were having success with Hydra's prior to the patch, they certainly haven't gotten worse.

Solution 2:

Can an army of hydras and speedlings can be enough to handle a powerful Terran army?

For any type of equivalent army (unless you have a LOT more hydras)... no.

You need to be into the baneling thing, otherwise you are using the wrong tool for the job.