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especially with the trend of many wallets to use mBTC instead of BTC.
That will be the main consideration. Since bitcoin has other names for smaller units (mBTC, uBTC, sat), there will be other suggestions to create symbols for other units. Too many symbols will only confuse the user.
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I would even go so far as to say that if ANY of the major wallets (Core, Electrum, Armory) come up with their own symbol just to do it for their wallet, the others developers would probably go with it for theirs too.
Just reading the bitcoin wiki, it seems the symbol in the OP is the priority of choice for some developers.
This symbol has been adopted by multiple Bitcoin services including satoshilabs.com (Trezor), SatoshiCap.net, pricedinbitcoin21.com, Thunderhub.io, bitcoinicons.com, thebitcoinmachines.com, and many more.
Btw, at first glance it looks like Facebook's Libra symbol, just imagine people might think libra has actually been launched.