A new policy memorandum release by US Citizenship and Immigration Services November 30, 2019 sets forth criteria where a final interview for an I-751 Petition to Remove Conditions on Permanent Residence may be waived. However, while framed as a new policy, it appears to merely confirm existing policy and it seems unlikely that much will change.
When a couple files for permanent residence for a non-citizen spouse on the basis of marriage to a citizen, the length of the marriage at the time the case is approved caries legal significance. If married two years or more, the non-citizen spouse is awarded permanent residence without restriction – a status that doesn’t expire (although the green card received carries a ten-year validity period).
However, up until fairly recently most couples had still been married less than two years at the point of approval. Where this is the case, the non-US citizen spouse is granted “Conditional Permanent Residence” – a form of probationary permanent residence valid for two years. For the two-year validity period, this person has essentially all of the rights of any other permanent resident (to live in the US, work anywhere, and return to the US from foreign travel).
Near the end of the two-year period, a “Petition to Remove Conditions” must be filed on form I-751 to demonstrate the bona fide nature of the marriage during the time since approval. These are normally filed jointly by the couple, but may still be filed by the foreign national spouse alone if the couple isn’t still together.
While all initial marriage based green card cases result in a final interview, historically not all Removal of Conditions cases did – many were approved on paperwork alone and the new unrestricted green card would simply come in the mail. This was true even for “waiver” petitions where the foreign national filed alone. The statute required an interview, but also gave USCIS the power to waive the interview.
The new policy memo doesn’t make clear how decisions on the waiver of an interview were made previously, but does set forth four criteria for making determinations on interview waiver moving forward:
They can make a decision based on the record because it contains sufficient evidence about the bona fides of the marriage and that the marriage was not entered into for the purpose of evading the immigration laws of the United States;
For Form I-751 cases received on/after December 10, 2018, USCIS has previously interviewed the I-751 principal petitioner (for example, for a Form I-485 or Form I-130);
There is no indication of fraud or misrepresentation in the Form I-751 or the supporting documentation; and
There are no complex facts or issues that require an interview to resolve questions or concerns.

It appears that all four criteria would need to be met for an interview to be waived.
Taken together, the four criteria appear to closely track the circumstances where such interviews have been waived in the past. It remains unclear whether this memo simply codifies an existing formal policy or replaces an internal policy.