Depends on what you mean by specialist. Now many companies are calling general HR jobs 'specialist' to make the job sound bigger than it is., so being a specialist is actually not hard. For e.g. in my company most of the HR is specialist:

Business Partnering - Fancy name for generalist work
Talent Acquisition - Recruitment and job placement
C&B - Basic analysis and simple benchmarking of salary & benefit
L&D - Training program coordination and arrangement
HRIS - Systems administration of staff records

None of the above are really specialist jobs or have higher pay than normal HR if you ask me.

In most global MNCs I would say the total number of real HR specialist in all areas is probably < 30 and most are regional/global coverage.