Pretty sure it would just be their name now, but I’d probably just try to avoid having to as it would still feel a bit weird, but not as weird as a 50 year old calling someone Auntie so and so and Uncle whatever. To be honest though they’re all in their old age and I haven’t really kept in touch since my mum died so I probably don’t need to worry.
I have a couple of nephews and a niece who are only between 5 and 10 years younger than me so they sometimes call me Uncle Rich just to wind me up!
I still call them Auntie. Also call some of my mum’s friends Auntie. My mum’s closest friend has got the same first name as her but I genuinely thought she was a real auntie until I was quite embarrassingly old. I distinctly remember asking my granny why she named two of her daughters the same thing and getting laughed at quite a lot.
I don’t call my uncles Uncle but I do call one of my dad’s friends Uncle.
Still call my Aunts and Uncles, Auntie… or Uncle…, I grew up seeing most of them every weekend so both my siblings and cousins all still use the Antie/Uncle prefix, it would seem weird to me not calling them that.
Always call them auntie (name)/uncle (name) but I think this is cos of my mum’s culture. I call my mum’s sister “tía” and only use her name if talking about her to someone else, and if I’m talking to a cousin I’ll just call them “primo/prima” half the time and use their name the other half.
My nephew just calls me and the TV by our names, no auntie or uncle, which I find weird but I guess it’ll make it easier when he’s older.