Predictive text programs have been around for a long time, and many are still available. The first one I came accross was Brown Bag Software’s "MindReader", which arrived on a 5.25in floppy disk in the early 1980s.
MindReader read what you were typing, guessed what the word might be, and popped up a numbered list of choices. You could then insert a whole word by selecting the one you wanted. If you didn’t want any of them, you just carried on typing.
Many predictive text programs use the PC’s function keys to make the selection
If you take this route, the best program for your purposes could be SumitSoft’s Typing Assistant. Its features include word prediction, auto-complete, auto-correct and, for abbreviations, auto-expand. It has a Skilled Typist Mode for translators, secretaries, authors, programmers and so on and an Unskilled Typist Mode for people who have problems spelling (including in 50+ foreign languages) or physical disabilities. It costs $129.95 but there’s a 30-day money back guarantee. FastKeys is a cheaper alternative