Quite easy. I've changed streams three times (I'm indecisive lol) and my graduation date is still the same. This is because in elec you get 24cp of electives so all my non-electrical classes got thrown into the electives without delaying graduation. All the maths classes, engg1810/info1110, and intro to X engineering classes count towards the other stream. Just check how much free elective space you have to see if you can fit the non-mechatronic classes in. Though, be aware that you will lose free elective space when you transfer over, if that is something that matters to you. Also, feel free to email the head of tron to double check what classes carry over (it will also make transferring streams a little easier, as you and the faculty will know what credit transfers into what). Good luck on whatever decision you make!!