we're talking dropped bars, right? IME if you ride much along a towpath/gravel the transmission will get dirty pretty quickly and will wear out rather more quickly than in (relatively) nice clean road use.
Possible changes might range from minimal to maximal.
Minimal changes might be
- new 7/8/9s wear parts, with revised shifters (or just mounts eg Kelly take-offs) to suit. Same brakes etc. Advantages would be prang-proofness, separation of brake and gear functions (allowing easier repairs/changes) and ongoing cost of consumables.
Maximal changes might be to change to 2x10 or 2x11 groupset eg GRX chainset and mechs, with Tiagra 4700 2x10 STI controls or Shimano 105 2x11 STI controls. You would need to fit mini-Vs with these brake levers. Advantages are that it is 'more modern'. GRX mechs allow use of a wide range cassette so you can get lower gears with a 2x format. GRX chainset allows use of 46-30 chainrings (long favoured as an 'Alpine double'). Downsides are cost, crash proofness, and ongoing cost of consumables.
You can make any transmission last reasonably well if you are prepared to maintain it. However if you are a 'replace it all when it is worn out and as little maintenance in the meantime as possible' then it will turn out expensive; especially shimano 10/11s chainrings are an arm an a leg to buy, and so are cassettes, relatively speaking.
cheers