In an effort to create an upgrade path from an Angular 2 app to Angular 4, this is what I changed to accomplish just that.

Do note:

• This web app predates Angular CLI and is loaded via SystemJS and not webpack.
• This effort is an instant 60% reduction in bundled Angular library code.
• Is backwards compatible with Angular 2.

tsconfig.json – BEFORE

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": true,
    "noImplicitAny": true,
    "suppressImplicitAnyIndexErrors": true,
    "types" : []
  },
  "exclude": [
    "node_modules"
  ]
}

tsconfig.json – AFTER

{
  "compilerOptions": {
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "module": "commonjs",
    "moduleResolution": "node",
    "noImplicitAny": true,
    "removeComments": true,
    "sourceMap": true,
    "suppressImplicitAnyIndexErrors": true,
    "target": "es5",
    "types" : []
  },
  "exclude": [
    "node_modules/*"
  ]
}

package.json – BEFORE

{
  "dependencies": {
    "@angular/common": "2.4.6",
    "@angular/compiler": "2.4.6",
    "@angular/compiler-cli": "2.4.6",
    "@angular/core": "^2.4.6",
    "@angular/forms": "2.4.6",
    "@angular/http": "2.4.6",
    "@angular/platform-browser": "2.4.6",
    "@angular/platform-browser-dynamic": "2.4.6",
    "@angular/router": "3.0.0"
  },
  "devDependencies": {
    "concurrently": "^2.2.0",
    "lite-server": "^2.2.0",
    "typescript": "^2.0.2",
    "typings": "^1.0.4"
  }
}

package.json – AFTER

{
  "dependencies": {
    "@angular/common": "^4.0.0",
    "@angular/compiler": "^4.0.0",
    "@angular/core": "^4.0.0",
    "@angular/forms": "^4.0.0",
    "@angular/http": "^4.0.0",
    "@angular/platform-browser": "^4.0.0",
    "@angular/platform-browser-dynamic": "^4.0.0",
    "@angular/router": "^4.0.0"
  },
  "devDependencies": {
    "@types/node": "^6.0.60",
    "concurrently": "^3.1.0",
    "lite-server": "^2.3.0",
    "typescript": "^2.2.2"
  }
}