import re

s = "Hi, domain: (foo.bar.com) bye. So long"

print(re.findall(r'(?:^|\b)(\w+(?:\.\w+)*|\W+)(?!\.\w)(?=\b|$)', s))

print(re.findall(r'(?:^|(?<!\.)\b(?!\.)).+?(?=(?<!\.)\b(?!\.)|$)', s))