Agreed. You can basically stop trying to prompt them to follow up with you (since they are non-responsive / won't suggest next steps typically in this scenario).
Another tough thing to balance is the flip of this - how to politely drop a VC you do not want to talk to further, who is interested in your company and knows you are fundraising...
Understand that some (many?) VC's understand that saying "no" explicitly can hurt your prospects with other VCs (you will be asked to explain why that other VC said "No" which is impossible to do usually because you don't have the complete picture). So they let it drift quietly silent and understand when "you are really busy and might not get back to them for a while."