On this issue, see the solution proposed in the working draft of the alignment of INSPIRE metadata with DCAT-AP.

As the proposal is to replace a property that is in DCAT by another that serves the same function, this proposal fails on criterion 2:  Ensure compliance with DCAT.

Please note that the INSPIRE proposal still uses dct:spatial as the property to express location.

Do I understand this correctly, that the property in line with INSPIRE approach IS dct:spatial? If not, what is the replacement proposed?

Yes, you understand correctly, dct:spatial is what INSPIRE recommends.

The proposal in the working draft of the alignment of INSPIRE metadata with DCAT-AP is to use dct:spatial + locn:geometry + a GML literal. I'm copy-pasting here the example you can see by clicking the link above:

[] dct:spatial [ a dct:Location ;
       locn:geometry "<gml:Envelope srsName=\"http://www.opengis.net/def/EPSG/0/4326\">
                        <gml:lowerCorner>-10.58 34.56</gml:lowerCorner>
                        <gml:upperCorner>34.59 70.09</gml:upperCorner>
                      </gml:Envelope>"^^gsp:gmlLiteral ] .

Whether the use of GML is the preferable solution for encoding the bounding box is still an open issue, that is likely to be addressed in GeoDCAT-AP.

With the information that the INSPIRE approach to alignment uses dct:spatial, the issue can be closed.