No viability whatever.
Before the Civil War, abolitionism was very much a minority sentiment. In 1844, 97.6% of Americans voted for slaveowners Henry Clay and James Polk; only 2.3% voted for anti-slavery candidate
James G. Birney. "Free Soil" candidates did much better, but "Free Soil" meant the exclusion of slaves from the Territories, not their emancipation in the slave states. Indeed, many Free Soilers wanted the complete exclusion of blacks from the Territories.
Slavery was practiced in several northern states as of 1790, including NY, NJ, CT, and RI. It was ended by laws decreeing gradual emancipation and free birth. But even this was controversial, and most of the slaves were sold south instead of being freed.
In short, almost no one wanted to free slaves, much less pay for it. Note that by 1860, the slave population had an aggregate value of at least two billion dollars, while the entire budget of the US government was only about 70 million dollars.
And most whites found the presence of free blacks in any significant number disturbing. The only general emancipation program to find
any support was the colonization movement, which sent a very small number of free blacks "back to Africa".
There was considerable prejudice against free blacks in the north. Illinois had a law barring all free blacks, though it wasn't enforced AFAICT. In New York City, the horse-drawn street cars were segregated until 1854. (In that year, a young colored woman sued the street car company and won; she was represented by future President Chester Arthur.) Working-class Irish immigrants were very hostile to free black competition for jobs.
In the Lincoln-Douglas debates in 1858, Lincoln found it necessary to assure Illinois voters that "I have no purpose, directly or indirectly, to interfere with the institution of slavery in the States where it exists. I believe I have no lawful right to do so, and I have no inclination to do so."
So I can't see any way that such a program could have been enacted.