May peace be with you.
In my humble opinion, there is no cogent warrant to understand
'ummatin' in the context of verse 3:110 as a reference which also includes future generations of Muslims including those today.
In my view, this is a specific reference to some of those during the Prophet’s ministry who were sincere believers of the message and who called for good. The latter is also supported by the context of previous verses such as verse 3:104, which speaks to those contemporaneous to the Prophet's ministry in the first instance.
003.104 "And Let there be among you a people (ummatun) inviting to all that is good, enjoining what is right, and forbidding what is wrong. These are the successful ones."Today, Muslims are a diverse people of numerous communities with arguably good and bad in all of them. The Arabic word
'Ummah' simply means a nation, a people, a race, a distinct body of people, family or a particular community which at times have certain characteristics which are common to them. It is normally the context in which the term is used which best intimates who it intends to capture.
I hope that helps, God willing.
Joseph.
REFERENCES:[1] Source and further discussion:http://quransmessage.com/forum/index.php?topic=728.msg2699#msg2699[2] We are the Best Ummah - Are we Really?http://www.facebook.com/joseph.a.islam/posts/248507105286424