I see... but isn't that a bit of a mess? If I want to run a full node, now I need to run 2 different folders with 2 different software with 2 different clients just to go between formats?
Wouldn't it be better to have it all inside the same software and be able to select what you want or maybe that would make newbies too confused and it's better that newbies use segwit by default (since they don't know anything about this anyway and sometimes excess of options make newbies stressed)? But then again, advanced users like myself would suffer from having to run 2 softwares..
No, you do not need to run two different softwares with their own datadir. Bitcoin Core has functionality now to have multiple wallets loaded at the same time. This is known as multiwallet. So how it would work is that you create one wallet which is set to only ever make segwit addresses, and another wallet which is set to only ever make non-segwit addresses. When you want to send, you choose the wallet you want to send from. When you want to receive Bitcoin, you choose the wallet you want to receive to and you will get an appropriate address. Note that this is all still in development and still in the design phase, so this could change and not be the actual final design.
That sounds good, I hope that the GUI is user friendly when managing the different wallets. How many wallet.dat files can you manage at the same time? I would like to have a "savings one", "spending one", another one for segwit addresses.. etc.
When somebody asks you for your Bitcoin address because they want to send you some, give them the bolded address.
12sziC91z7hwfpVDNw7UbsisaapBwFtW7t
337cKTRkrmfXHMRKgk1xosqsEY6dToRD7h
bc1qzjw3jywhf2r7k24y3gqj0fs4apddg03pujsjzx
Each of those represents the same Bitcoin key, but they are very clearly different. You will always be able to use the legacy Bitcoin address format, aka the first one. I can't imagine any wallet software not letting you see a legacy version address of any of your public keys.
What is the difference between using the native segwit format (that begins with b) from the one that begins with 3?
Is it just a temporal way to use segwit until the ones that begin with b are available or there are any pros and cons?