Your credit line is going to be specific to you, based on a credit card company’s interpretation of your credit history. There isn’t necessarily going to be some blanket policy out there about how much credit they’re willing to extend to customers.
Just because you had $10,000 in total credit with them back in the day doesn’t mean you’ll get $10,000 today. It doesn’t even mean you’ll be limited to $10,000. If your financial situation has (in their eyes) improved, they might offer a higher limit. If they are concerned about your ability to pay, they may keep your limit where it is.
They will take your total outstanding credit into account, including that at other banks.
I have several quite large credit lines, including one from Chase for the Freedom Card that replaced their AGR card. If I actually used them, I would rapidly exceed my ability to repay. My experience is they don't really look too hard at the dollar amount of open credit lines, as long as they are mostly
unused. If your outstanding balance is a significant percentage of the open credit lines is utilized, that will ding you as it will start lowering your credit score. If it use exceeds 50% it will really adversely affect your credit score.
BOA tends to be a bit conservative on credit limits particularly on newer cards. But if you have a good credit score (which will incorporate your amount of credit utilization), income, and, in particular, history of responsible credit usage with BOA itself, chances are good.
A human isn't going to look at it and the only outside information the computer algorithm is going to use is the credit score, that is where the outside credit line info really counts is how it affects the score.
I'd go ahead and request an increase to 10K a little bit after the cutover. I wouldn't explain that reason though and just request it via the website.
The only thing I'd worry about is it'll probably generate a "hard hit" inquiry on you credit profile. If you are planning to apply for another loan in the near future that's a factor, as most credit grantors look adversely on multiple credit applications in a short period of time.