I'm not proud of this, but it looks like it could work

main.tf

@@ -33,7 +33,7 @@ variable "enable_dns_support" {
 
 variable "enable_eks_support" {
   description = "When set to true, properly tags VPC assets with proper discovery assets"
-  default     = "true"
+  default     = false
 }
 
 variable "eks_cluster_name" {
@@ -45,15 +45,7 @@ resource "aws_vpc" "mod" {
   enable_dns_hostnames = "${var.enable_dns_hostnames}"
   enable_dns_support   = "${var.enable_dns_support}"
 
-  tags = "${var.enable_eks_support == "true" ?
-    map(
-      "Name", "${var.name}",
-      "kubernetes.io/cluster/${var.eks_cluster_name}", "shared",
-    ) :
-    map(
-      "Name", "${var.name}",
-    )
-  }"
+  tags = "${zipmap(compact(split(",", var.enable_eks_support == true ? "Name" : "Name,kubernetes.io/cluster/${var.eks_cluster_name}")), compact(split(",", var.enable_eks_support == false ? "${var.name}" : "${var.name},shared")))}"
 }
 
 resource "aws_subnet" "public" {