I am afraid I dont have a definite answer but the only way to find out can be by doing some testing and finding out if users are willing to use Twitter\Facebook\Google login credentials as the two user research studies I found show that many users may not be willing to use those login options if an existing login already exists
To quote this article from mail chimp
I did a little extra analytics footwork to see just how many people
were clicking the social login buttons. I was shocked to see that just
3.4% of the people that visited the login page actually used Facebook or Twitter to log in.
Similarly this study by typepad has similar results and shows that most users prefer to use the type pads login option as opposed to other open authentication options. To quote the article
To find out which services people are using to log in, I contacted
Jonathan March, Six Apart's Data Architect. I found out that while we
don't track every log in specifically, we can get a very rough
estimate by looking for a URL in a user's ID. Though the data is a bit
out of date, I think it is still very useful.
That said this data is based upon the fact that users already have a login and people might not be willing to try a new login option even though its a social login. To continue with the study, the study states that surprisingly most of of the new logins came via open authentication. To quote the article
What about sign up?
The previous graphs are based on data about users who have LOGGED IN
in the past few months. What about new users - users who have SIGNED
UP recently? Luckily Jonathan thought of this and followed up with
data and graphs on the growth of alternative authentication providers.
The results are a bit shocking.
User sign ups between 2 and 3 months ago (June 28 to July 28)
User sign ups between 1 and 2 months ago (July 28 to Aug 28)
User sign ups in the past month (Aug 28 to Sept 28)
OpenID user sign ups by provider by week
That said, I recommend reading this article about which open authorization option to choose if you decide to go that route