I think you are right some scholars would hesitate to ban outright something that was permitted at the time of the prophet, even though the prophet made it clear it was distasteful. The early community had to tackle the issue around them and no-one denies the thrust of islamic guidance was to free slaves and effectively abolish it in that way.
Wikipedia has this to say on Muhammads view on slavery for example
"Muhammad encouraged manumission of slaves, even if one had to purchase them first. Traditional biographies of Muhammad give many examples where Muhammad's companions, at his direction, freed slaves in abundance. Abul Ala Maududi reports that Muhammad freed as many as 63 slaves.[3] Meer Ismail, a medieval historian, writes in Buloogh al Muram that his household and friends freed 39,237 slaves.
Therefore some scholars have argued that the eventual ban on slavery was intended and therefore is the current postion
Why do people try to argue that Islam ended slavery? Is there a verse in the Quran that prohibits it? Islamic slavery lasted until the 20th century. It was more benevolent than the western slave trade, but lasted much longer. What Muhammad did was establish it as a fixture with restrictions on it. It had to end eventually though- slavery, modernity, and human rights don't mix.
Since slavery is permitted by Islamic law, Muslim countries have used secular law to ban it. Some countries outlawed slavery only comparatively recently:
* Qatar in 1952
* Yemen and Saudi Arabia in 1962
* Mauritania in 1980
Internal pressure came from a variety of Muslim sources:
From the 1870s, radical and gradual rationalists, together with moderate literalists and progressive ulama, could all be placed in the broad category of opponents of slavery, despite their manifold disagreements.
William G. Clarence-Smith, Religions and the abolition of slavery - a comparative approach
Initially, it was a source of great hostility that the West dared to intervene in Islamic affairs in contradiction to what was allowed by the Koran.
But as Western influence, or modernism, became more and more [widespread], it became less fashionable as well as profitable in Islam to own slaves. And it became illegal over much of the area.
The pressures against slavery were extremely great from Western powers. It was the moral issue. It became more scandalous because the conditions of procurement and transport became more and more horrendous.
Ronald Segal, interview with Suzy Hansen, Salon Magazine, 2001
Topic: Famous Muslim to infamous Murtad