It is extremely easy for a government to convince people to use their new currency, they already do it just by enforcing tax payments be paid in their local fiat currencies.
[1] https://bitcoinmagazine.com/19418/bitcoin-friendly-bills-unv...
2. States don't have their own currencies, so other than the ease of use of US Dollars, they really wouldn't care what you pay your taxes in, so long as they can use it.
So yes, a government could set up an e-currency and make us use it, but there's no way a government could (intentionally) set up a currency like bitcoin. Truly algorithmic e-currency is fundamentally incompatible with the concept of governing. Anything by a government would allow reversals, currency injections, invisible transactions, etc.
(1) What difference does "direct lineage" have? They aren't gold, and they aren't backed by gold. Unless you arguing that they have sentimental value from a historical association that hasn't been real for generations, this is meaningless.
(2) Also, this is more true of silver than it is of gold. the gold standard was sort of a brief fad (in long-term historical terms) in the final centuries of commodity currency standards as the dominant model, while silver had dominated for a much longer time previously. Pretty much all of the extant currencies that have a "direct lineage from gold" also have a direct lineage from silver, and the ones that aren't themselves relatively new have a much longer history under silver.