Starting Lego robotics projects low-budget with the intention of expanding later
According to the WeDo 2.0 FAQ

Is this a new plug system?
Yes, this is the new LEGO Power Functions plug that has been optimized also to meet potential future needs.
What does that mean for the existing plug systems on other Power Function and MINDSTORMS products? Will they also be changed?
Yes, eventually we will convert to the new plug system after a transition period. The exact timing of this transition has not been determined.

However, if you want to build something today, WeDo is a good choice since it is compatible with the current Power Functions products.
There is also the 3rd-party SBrick that works with current Power Functions products but uses Bluetooth Low Energy like WeDo 2.0.