On Wed, Apr 26, 2017 at 4:01 PM, Luke Dashjr via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> There are things scriptSig can do that witness cannot today - specifically
> add
> additional conditions under the signature. We can always obsolete scriptSig
> later, after segwit has provided an alternative way to do this.
>

I'm not sure what you are referring to here.  The data in the scriptSigs
are never signed.  The scriptSigs are always stripped from the transaction
before the sigHash is made.