The use case is to create as few as possible OMOP codes outside LOINC.
OMOP CDM uses LOINC and embraces it.
Recently, there are efforts to better capture LOINC parts in OMOP Vocabulary. See here https://forums.ohdsi.org/t/improve-loinc-representation-in-omop-vocabulary-athena-link-parts-to-lab-tests/7925
Knowing the LPs (including temporary ones) is crucial for following correctly LOINC concept model.
LOINC will at some point adopt some framework for postcoordination.
As terminologist, I have few thoughts on how from components one could create good classification codes.
E.g., test from sputum for SARS-CoV-2, test from sputum for SARS-CoV-2 RNA,
The LOINC search supports such nice searchers (unfortunately not for temporary codes). e.g. https://search.loinc.org/searchLOINC/search.zul?query=hiv+1+RNA+Methodless%3Atrue
search is: ‘hiv 1 RNA Methodless:true’
The release of those codes was coordinated with SNOMED CT (per here http://www.snomed.org/news-and-events/articles/changes-coronavirus-descriptions ) which is great. I like that LOINC has temp codes published and can respond more flexibly. No temp code page for SNOMED CT 
I would also like to propose a LOINC group for SARS-CoV-2 tests. (and have concept of temp groups (inbetween releases).
I would like to propose at least one (or several) methodless codes for SARS-CoV-2
In fact there should be a policy for methodless codes accross all of LOINC lab content. (and it should be consistent) (or some postcoordination grammar (expression language) where my expression is deemed equivalent to an existing pre-coordinated code.)
I would also like to see parent-child hierarchy between LP for ‘SARS-CoV-2 RNA’ and LP ‘SARS coronavirus 2 N gene’
And be able to search for any component that is child of ‘SARS-CoV-2’ or ‘SARS-CoV-2 RNA’
(that in fact assumes temp codes do show up in <b>the </b>LOINC search page.)
p.s.
By the way, upgrading this forum to some newer platform would be great. (allow ctr+V to insert image in my post)
