That's a pretty vague question as there as so many variables. It depends on many things like if it's tuned right to how you drive it to what's done to it, etc.
Well, if you have an original T-45 gearbox; those things are prone to failure. If you experience grinding gears while doing regular up shifts, especially going to 3rd, shifter gets stuck into reverse; etc. Then you may have problems down the road. An aftermarket shifter with shifter stops would be a good idea to get if you don't have one now. It may or may not prevent further degradation of the gearbox. These things have weak shifter forks, I was told by the tranny guy when he was rebuilding mine, that when he ordered replacement parts; they came with the upgraded forks.
Now the engine. If you keep it normally aspirated and put in bolt on parts, keep it tuned, use good oil and change it frequently and generally don't abuse it; will give you good service. Now if you add power adders such as forced induction and/or nitrous, count on problems sometime down the road. The weak points of these engines are the hypereutetic pistons and rings and the stock connecting rods. Also, the cylinder head gaskets seal well; too well in fact. Say you are using a 150 shot of nitrous, the tune is so-so, and the engine runs really lean when you NAWS it , generally the head gaskets function like a pop-off valve on a pressure cooker, too much pressure and the valve opens up to release pressure. Same with head gaskets, too much cylinder head pressure and then the gaskets are designed to blow. 4.6 gaskets have been known not to blow when trouble started while using power adders.
The 8.8 is pretty stout as-is. But if you start using stickier tires like drag radials or slicks and start dumping the clutch at 4000 rpm and the car hooks, then you may have problems down the line. Scratch that- you will have problems eventually. Getting good quality 31 spline axles and a getting an outside cover like a T/A Performance girdle for added bearing cap strength, is recommended.
Also, one of your first mods to get is quality sub frame connectors for the chassis. Regular length is mandatory IMO, full-length is optional.