Your question is, can the irregular heart rate ever get back to normal rhythm in the case of Atrial fibrillation?
The answer is YES and NO.
It depends entirely on the cause.
1)AF can be due to a damaged or "strugggling heart" in which case it is permanent despite treatment OR
2)AF can be caused by a temporary or external cause.
Examples of 1) the permanent type are high BP, atherosclerosis, overactive thyroid, asthma, COPD and many , many others.
Examples of 2) include drinking excess coffee, taking illegal drugs.smoking and many many others.
Sorry about the inconclusive answer.............but there you go!!!