My dc were all early talkers.
Dd1 was full 6-7 word sentences by 20 months. At 21 we were staying with my dp and my dm loves to repeat how she asked her to choose something and she replied with "I'll be moment, tause I'll have to consider."
Dd2 was an earlier speaker, used it to great effect to make sure her presence was felt 
She hit the "why" stage at 15 months which was very tiring. She was also an early walker, to contradict all the people that say children do one or the other.
Ds wasn't as good as the others, but once he'd had his grommets put in at 20 months he caught up very quickly, within a month.
All of them were reading basically round about the age of 2, and reasonably fluently by 2.6yo.
BUT they're aged 12, 9 and 5 and they're all competant on the English side, but not outstanding. They're all much more mathematical as me and dh are.
And I don't know why they were such talkers, neither me or dh are big talkers, and the only one of the dc who you'd describe as a chatterbox now is dd2, and even then she's not that talkative.
I remember with dd1, I had a friend whose dc1 was born within a month of dd1. Her dc1 was referred to SALT at 2yo for saying almost nothing-I think it was 4 words. We lost contact for a while and re-met when our dc were aged about 4.6yo, and you couldn't have told the difference in speech between them. You certainly couldn't have picked out who was an early talker and who needed intervention to get talking. It was so lovely to hear after I knew that there'd been so much worry over her speech.
I do think that for most children, it's one of those things that they do or they don't and it shows very little for the long term.