Other researchers have combined sequencing approaches in order to improve inferences made from amplicon sequencing data (55)⁠. Since vertical gains and losses of genetic information are common in prokaryotic world, there is a substantial probability of error associated with functional assignment of taxa based solely on 16S identities.
To circumvent this recognized limitation, metagenomic and metatranscriptomics analyses are increasingly being used to describe the functional gene diversity and expression in various environmental samples, although both sequencing and bioinformatic efforts needed for gaining functionally relevant insights into ecosystem processes by these approaches are usually magnitudes higher than those needed for analyzing amplicon sequencing data.  
Section overview: Now that we have applied amplicon sequencing for over a decade, what are our next steps as a field? How can we expand upon what we already know to generate improved ecological insights?
1. Using amplicon sequencing to plan 'targeted-metagenomics' experiments (ie SIP experiments, reduced metagenomes) - this will allow us to unequivocally link community structure to organisms and their functions
2. Testing hypotheses generated using amplicon sequencing - combining next-generation sequencing with traditional microbiology ( https://doi.org/10.1038/s41579-020-00458-8)