If it's really high it will probably still be quite high but there are three potential consequences:
1 -- your "available credit" will go down so your utilization ratio will increase. Now if you have very low credit usage already and pay in full each month, this will be a minor hit and may not be a hit at all.
2 -- The "average age" of your open accounts will decrease -- the older the account you close, the more the "average age" will decrease and the bigger the hit -- but probably still not major.
3 -- Opening a new account and applying for new credit can put a "hard pull" on your account which can impact the score. (Again, if you've not applied for any other credit in the last two years, the impact will be small.)
I doubt that your score would drop all that much -- and if that would still leave you in "prime" territory, say 750+ on the FICO, it's much ado about nothing.